ArticleLiterature Review

Alvarez-Pellitero, P. Fish immunity and parasite infections: From innate immunity to immunoprophylactic prospects. Veterinarian Immunology and Immunopathology

Authors:
  • Spanish National Research Council, Instituto de Acuicultuta Tore de la Sal, Castellón, Spain
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Abstract

The increasing economic importance of fish parasitoses for aquaculture and fisheries has enhanced the interest in the defence mechanisms against these infections. Both innate and adaptive immune responses are mounted by fish to control parasite infections, and several mechanisms described for mammalian parasitoses have also been demonstrated in teleosts. Innate immune initiation relies on the recognition of pathogen-associated molecular patterns (PAMPs) by pathogen recognizing receptors (PRRs). A number of PRRs, mainly Toll-like receptors (TLRs), have been characterized in fish, and some molecules susceptible of functioning as PAMPs are known for some fish parasites. A lectin-carbohydrate interaction has also been described in some host fish-parasite systems, thus probably involving C-type lectin receptors. Inflammatory reactions involving cellular reactions, as phagocytosis and phagocyte activity (including oxidative mechanisms), as well as complement activity, are modulated by many fish parasites, including mainly ciliates, flagellates and myxozoans. Besides complement, a number of humoral immune factors (peroxidases, lysozyme, acute-phase proteins) are also implicated in the response to some parasites. Among adaptive responses, most data deal with the presence of B lymphocytes and the production of specific antibodies (Abs). Although an increasing number of T-cell markers have been described for teleosts, the specific characterization of those involved in their response is far from being obtained. Gene expression studies have demonstrated the involvement of other mediators of the innate and adaptive responses, i.e., cytokines [interleukins (IL-1, IL-8), tumor necrosis factor (TNF), interferon (IFN)], chemokines (CXC, CC), as well as several oxidative enzymes [inducible nitric oxide synthase (iNOS), cyclo-oxygenase 2 (COX-2)]. Information is scarcer for factors more directly linked to adaptive responses, such as major histocompatibility (MH) receptors, T cell receptors (TCRs) and IgM. Expression of some immune genes varied according to the phase of infection, and proinflammatory cytokines were mainly activated in the early stages. Gene expression was generally higher in the target tissues for some skin and gill parasites, as Ichthyophthirius multifiliis, Neoparamoeba spp. and Lepeophtheirus salmonis, thus confirming the relevance of mucosal immunity in these infections. The existence of protective responses has been demonstrated for several fish parasites, both in natural infections and in immunization studies. Most information on the mechanisms involved in protection deals with the production of specific Abs. Nevertheless, their levels are not always correlated to protection, and the precise involvement of immune mechanisms in the response is unknown in many cases. No commercial vaccine is currently available for piscine parasitoses, although experimental vaccines have been assayed against I. multifiliis, Cryptobia salmositica and scuticociliates. The known information points to the need for integrated studies of the mechanisms involved in protection, in order to choose the optimum antigen candidates, adjuvants and formulations.

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... In line with the reports of Hong et al. [54] who reported an increase in IL-1β and TNF-α, proinflammatory cytokines produced by macrophages during inflammatory responsein Japanese flounder within few hours of exposure to outer membrane vesicles, levels ofthese cytokines were significantly increased transiently in the present study. Similarly, a significant increase in the chemokine CXCa, involved in conferring resistance to pathogens by directing the migration of immune cells to the infection site [55], on 42 d. p.i. again indicates stimulation of immune response by rOmpC immunization, which is in agreement with earlier reports on rOmpF-immunized L. rohita [26] and vaccinated Japanese flounder [56]. ...
... An upregulation of the C3 expression in the rOmpC-immunized L. rohita on day 28 and day 42 indicates activation of the complement system of L. rohita, linking the innate and adaptive immune response, as also noticed in earlier vaccination experiments [48,49]. The alternative pathway of complement system comprising C3 helps in activation of adaptive immune response, killing of pathogens by opsonization and activation of phagocytes [55]. The binding of C3 to rOmpC could have resulted in rOmpC processing and activation of downstream pathway leading to its phagocytosis and activation of antibody (IgM) synthesis. ...
... Similarly, up-regulation of both lysozyme G and lysozyme C, important defense enzymes produced by monocytes, macrophages, and neutrophils involved in protection from microbes by their lytic mechanism [55], in the rOmpC-immunized L. rohita head kidney tissue both at an early and later time points strengthens the ability of rOmpC to stimulate innate immune molecules. In zebrafish vaccinated with live attenuated Vibrio anguillarum, an increase in the lysozyme expression was noted only at early time points [57]. ...
Article
Aeromonas hydrophila is an opportunistic pathogen that causes enormous loss to aquaculture industry. The outer membrane proteins of Aeromonas help in bacterium-host interaction, and are considered to be potential vaccine candidates. In the present study, we evaluated immunogenicity and protective efficacy of recombinant OmpC (rOmpC) of A. hydrophila in Indian major carp, Labeo rohita. The rOmpC-vaccinated fish produced specific anti-rOmpC antibodies with a significant antibody titer, and the antisera could specifically detect the rOmpC in the cell lysates of Escherichia coli expressing rOmpC and cross-react with different Aeromonas lysates, indicating the suitability of the anti-rOmpC antisera to detect Aeromonas infection. A significant increase was noted in ceruloplasmin level, myeloperoxidase and anti-protease activities in transient and temporal manner the sera of the rOmpC-immunized fish as compared to PBS-control fish. Higher agglutination- and hemolytic activity titers in the anti-rOmpC antisera indicate stimulation of innate immunity. Expression of immune-related genes comprising various acute phase proteins, cytokines and inflammatory response molecules were modulated in the head kidney of rOmpC-immunized L. rohita. While IgM, IL1β, and TLR-22 were significantly up-regulated at early time points (3 h–72 h), the others showed a transient augmentation at both early and later time points (SOD, lysozymes C and G, NKEF-B, C3, CXCa and TNF-α) in the rOmpC-immunized L. rohita in comparison to PBS-injected controls. These data suggest that the rOmpC-induced immune response is temporally regulated to confer immunity. In vivo challenge of the rOmpC-immunized fish with A. hydrophila showed significantly greater survival when compared to PBS-injected control fish. Thus, our results highlight the immunomodulatory role of rOmpC and demonstrate its protective efficacy in L. rohita, along with the use of anti-rOmpC antisera in detecting Aeromonas infections.
... In line with the reports of Hong et al. [54] who reported an increase in IL-1β and TNF-α, proinflammatory cytokines produced by macrophages during inflammatory responsein Japanese flounder within few hours of exposure to outer membrane vesicles, levels ofthese cytokines were significantly increased transiently in the present study. Similarly, a significant increase in the chemokine CXCa, involved in conferring resistance to pathogens by directing the migration of immune cells to the infection site [55], on 42 d. p.i. again indicates stimulation of immune response by rOmpC immunization, which is in agreement with earlier reports on rOmpF-immunized L. rohita [26] and vaccinated Japanese flounder [56]. ...
... An upregulation of the C3 expression in the rOmpC-immunized L. rohita on day 28 and day 42 indicates activation of the complement system of L. rohita, linking the innate and adaptive immune response, as also noticed in earlier vaccination experiments [48,49]. The alternative pathway of complement system comprising C3 helps in activation of adaptive immune response, killing of pathogens by opsonization and activation of phagocytes [55]. The binding of C3 to rOmpC could have resulted in rOmpC processing and activation of downstream pathway leading to its phagocytosis and activation of antibody (IgM) synthesis. ...
... Similarly, up-regulation of both lysozyme G and lysozyme C, important defense enzymes produced by monocytes, macrophages, and neutrophils involved in protection from microbes by their lytic mechanism [55], in the rOmpC-immunized L. rohita head kidney tissue both at an early and later time points strengthens the ability of rOmpC to stimulate innate immune molecules. In zebrafish vaccinated with live attenuated Vibrio anguillarum, an increase in the lysozyme expression was noted only at early time points [57]. ...
... Due to large-scale intensive production facilities, fish are exposed to potential various pathogens that often result in massive economic losses (1). The disease resistance of fish mainly depends on the main defense organs' immune function (2). Skin, an important mucosal defense organ in fish, has developed a better barrier system (including physical barriers and immune barriers) to protect the whole body from natural pathogen invasion (3). ...
... In summary, the current work presented a clear outline of dietary MOS enhanced fish skin immune barrier and physical barrier function after infection with A. hydrophila. Our study confirmed that dietary MOS supplementation could improve the status of skin health, as demonstrated by the following findings (1): MOS supplementation enhanced the immune barrier function via increasing the skin disease resistance, producing antibacterial compounds and immunoglobulins, upregulating anti-inflammatory cytokines (except IL-4/13B), and downregulating pro-inflammatory cytokines gene expression (2). MOS supplementation protected the physical barrier function via increasing the antioxidant capacity, inhibited excessive apoptosis, and enhanced the tight junction barriers (except claudin-b). ...
Article
Full-text available
The objective of this study was to evaluate the efficacy of dietary Mannan oligosaccharides (MOS) supplementation on skin barrier function and the mechanism of on-growing grass carp (Ctenopharyngodon idella). Five hundred forty grass carp were fed for 60 days from the growing stage with six different levels of MOS diets (0, 200, 400, 600, 800, and 1,000 mg kg-1). At the end of the growth trial, the 14-day Aeromonas hydrophila challenge experiment has proceeded. The obtained data indicate that MOS could (1) decline skin lesion morbidity after being challenged by the pathogenic bacteria; (2) maintain physical barrier function via improving antioxidant ability, inhibiting excessive apoptosis, and strengthening the tight junction between the epithelial cell and the related signaling pathway (Nrf2/Keap1, p38MAPK, and MLCK); and (3) regulate immune barrier function by modulating the production of antimicrobial compound and expression of involved cytokines and the related signaling pathway (TOR and NFkB). Finally, we concluded that MOS supplementation reinforced the disease resistance and protected the fish skin barrier function from Aeromonas hydrophila infection.
... Estos epitelios están cubiertos por una capa mucosa que evita su anclaje (Pickering y Richards, 1980), y que tiene además un efecto tóxico, mediado por factores humorales (Roberts, 2001), siendo secretada de forma abundante (metaplasia mucoide) ante infecciones masivas de ectoparásitos (Bauer, 1961). Además, la expresión génica es significativamente mayor en estos tejidos diana, lo que confirma la importancia inmunitaria de la mucosa en este tipo de infecciones (Álvarez-Pellitero, 2008). ...
... Los ciprínidos, como la mayoría de los teleósteos, carecen de una médula ósea y de los nódulos linfáticos del sistema inmune presentes en mamíferos; sin embargo presentan órganos linfoides primarios (timo y pronefros) y secundarios (pronefros y bazo) (Hoole y cols., 2001), desarrollando inmunidad adquirida ante muchas enfermedades parasitarias (Bauer, 1961). De hecho, la existencia de respuestas de protección se ha demostrado frente a varios parásitos, tanto en infecciones experimentales como en estudios de inmunización, donde se constata la presencia de linfocitos B y de la producción de anticuerpos específicos, aunque también se han descrito varios marcadores de células T, y la implicación de otros mediadores de la respuesta innata y adquirida (citoquinas, factores de necrosis tumoral, interferón, etc.) (Álvarez-Pellitero, 2008). La principal inmunoglobulina de los peces es de la clase IgM (Dick y Choudhury, 1995a). ...
Thesis
Full-text available
The current PhD Thesis has a double approach: qualitative and quantitative. The qualitative part was based on the identification of the different parasites found in the fish of the mid and upper river Duero basin, through the morphological description and classification in different taxonomic groups. The quantitative part was designed as a transversal epidemiological study, with the aim of establishing the prevalence and intensity of infection of the different parasite groups identified, as well as establishing the most important associations between those groups and the risk factors that could be involved. The aim of the study was the species belonging to the Family Cyprinidae, the most characteristic and diverse in its aquatic ecosystems: Iberian barbel (Barbus bocagei), “bermejuela” (Chondrostoma arcasii), Duero nase (Chondrostoma duriense), Iberian chub (Squalius carolitertii), Iberian gudgeon (Gobio lozanoi), Eurasian minnow (Phoxinus phoxinus) and tench (Tinca tinca). The fish was chosen as sampling unit, and sampling which was randomized, stratified and distributed through three seasons (spring, summer and autumn), since 2005 to 2007. Seven sampling stations were selected: two of them in the upper part of the rivers Revinuesa and Ucero; four in the middle part of the rivers Arlanza, Duratón, Eresma y Ucero; and a single station in a tench fish farm. In total, eleven taxonomic groups were identified: three protozoans (Ichthyophthirius multifiliis, Tripartiella sp. y Myxobolus sp.), two monogeneans (Gyrodactylus sp. y Dactylogyrus sp.), two crustacean copepods (Ergasilus sieboldi y Lernaea cyprinacea), one digenetic trematode (Hysteromorpha triloba) and one mollusc glochidium (Unio sp.). For every parasite, prevalences and intensities of infection were measured in those fish in which they were identified, as well as the main risk factors associated to its presence, both intrinsic (species, sex, reproductive state (spawning), somatic condition factor…) and extrinsic (location, seasonality, water physic-chemical and microbiological water quality…). In general terms, our results show the close link between the different environmental parameters which are characteristic of the studied region, the adaptations in the life cycles and strategies of the different species of cyprinids to them, as well as the adaptation of the different taxonomic groups of parasites both to the environment and to the host in/on which they develop their life cycles.
... Greater prevalence of these myxozoans in river-exposed fish contributed to heavier overall infection burdens and richness; continued river exposure if fish were not transported to the laboratory would further increase infective dosage (Benda et al., 2015;Ray et al., 2012). New infectious agents accumulated during river entry may elicit host responses that were not activated for carrier-state infections, and this enhanced response may be deleterious due to cross-reactive immune responses (Alizon et al., 2013;Alvarez-Pellitero, 2008). The demands of osmoregulatory transition and new infections probably reduce the capacity of adult salmon to effectively respond to thermal, fishery, and other stressors, especially given limited endogenous resources (Kiessling et al., 2004). ...
Article
Incorporating host-pathogen(s)-environment axes into management and conservation planning is critical to preserving species in a warming climate. However, the role pathogens play in host stress resilience remains largely unexplored in wild animal populations. We experimentally characterized how independent and cumulative stressors (fisheries handling, high water temperature) and natural infections affected the health and longevity of released wild adult sockeye salmon (Oncorhynchus nerka) in British Columbia, Canada. Returning adults were collected before and after entering the Fraser River, yielding marine- and river-collected groups, respectively (N=185). Fish were exposed to a mild (seine) or severe (gill net) fishery treatment at collection, and then held in flow-through freshwater tanks for up to four weeks at historical (14°C) or projected migration temperatures (18°C). Using weekly nonlethal gill biopsies and high-throughput qPCR, we quantified loads of up to 46 pathogens with host stress and immune gene expression. Marine-collected fish had less severe infections than river-collected fish, a short migration distance (100 km, 5-7 d) that produced profound infection differences. At 14°C, river-collected fish survived 1-2 weeks less than marine-collected fish. All fish held at 18°C died within 4 weeks unless they experienced minimal handling. Gene expression correlated with infections in river-collected fish, while marine-collected fish were more stressor-responsive. Cumulative stressors were detrimental regardless of infections or collection location, likely due to extreme physiological disturbance. Because river-derived infections correlated with single stressor responses, river entry likely decreases stressor resilience of adult salmon by altering both physiology and pathogen burdens, which redirect host responses toward disease resistance.
... The fish immune system is divided similarly to that of mammals into an innate (non-specific) and an adaptive (specific) part (Alvarez-Pellitero, 2008;Magnadottir, 2010;Pastoret et al., 1998;Turner, 1994;Van Muiswinkel & Nakao, 2014). A threat to common carp aquaculture caused by emerging viral infections forced researchers to focus more intensively on the mechanism of resistance and immune response against particular infections. ...
Article
The importance of world aquaculture production grows annually together with the increasing need to feed the global human population. Common carp (Cyprinus carpio) is one of the most important freshwater fish in global aquaculture. Unfortunately, carp production is affected by numerous diseases of which viral diseases are the most serious. Koi herpesvirus disease (KHVD), spring viraemia of carp (SVC), and during the last decades also koi sleepy disease (KSD) are currently the most harmful viral diseases of common carp. This review summarizes current knowledge about carp edema virus (CEV), aetiological agent causing KSD, and about the disease itself. Furthermore, the article is focused on summarizing the available information about the antiviral immune response of common carp, like production of class I interferons (IFNs), activation of cytotoxic cells, and production of antibodies by B cells focusing on anti‐CEV immunity.
... Although vaccination has been used successfully in a number of aquaculture industries for disease prevention, especially in the global salmon farming industry (Alvarez-Pellitero, 2008;Bravo and Midtlyng, 2007;Gudding et al., 1999), their use is limited to juveniles and adults that have a more developed or functional immune system (Llewellyn et al., 2014). As a means to reduce mortality in the early life stages of fish and limit the spread and growth of pathogenic microorganisms, many production facilities have resorted to the use of chemical disinfectants for treating eggs and larvae (Liu et al., 2014;Llewellyn et al., 2016). ...
Article
The dusky kob Argyrosomus japonicus is an emerging aquaculture species in South Africa. To support industry growth, existing hatcheries frequently sell or donate excess eggs to neighbouring farms, raising concern over the potential transfer of infectious disease agents. Chemical disinfectants are frequently used to prevent transmission of diseases, but their application has shown large variations between finfish species and very little is known about the efficacy and impact of disinfectants on dusky kob eggs or larvae. A thorough understanding of the bacterial communities associated with specific fish species can inform the need for specific chemical agents and guide a more targeted approach for disease control and treatment. Therefore, this study used next generation sequencing (NGS, 16S rDNA gene) and downstream bioinformatics analysis to describe the bacterial microbiome associated with the eggs and rearing water of dusky kob. Four chemical disinfectants [chloramine-T (C-T), povo‑iodine (PI), hydrogen peroxide (H2O2) & formaldehyde (CH2O)], applied at different concentrations and times, were then tested for their ability to disinfect eggs and seawater. The impact of each disinfectant on early larval development was also assessed. A total of 11,605 individual bacterial operational transcriptional units (OTUs) were identified from the dusky kob egg (7352 OTUs) and hatchery water (4253 OTUs) samples. Non-metric multidimensional scaling (NMDS) analysis revealed distinct differences in the composition of the microbiota associated with the egg and seawater samples. A moderate level of bacterial diversity was observed in all samples, with the seawater samples dominated by Rhodobacteraceae (65%) and Flavobacteriaceae (14%); whereas egg samples were dominated by Pseudoalteromonadaceae (49%), Vibrionaceae (27%) and Colwelliaceae (8%). A classical univariate statistical comparison identified 6 differentially abundant OTUs at phylum level, 12 at family level and 19 at genus level; with members of the family Vibrionaceae found to be significantly (P = 0.0011) more abundant on dusky kob eggs samples. All tested chemical disinfectants were capable of reducing the bacterial load in seawater in a dose dependent manner, with the number of culturable bacteria on eggs decreasing significantly following exposure to PI and CH2O for five minutes (43% and 88% reduction in CFUs, respectively), compared with C-T and H2O2 (3% & 10%). Similarly, PI and CH2O significantly decreased the culturability of Vibrio species on eggs (79% & 75%), compared with C-T and H2O2 (12% & 14%). None of the disinfectants appeared to have any adverse impact on larval growth and morphology.
... Consistent with the above APPs, the expression of Alpha-2macroglobulin (A2M1, A2M2), TF (transporter transferrin), and FER (iron storage protein ferritin) were also significantly downregulated in the D/C and SI/C group during the advanced stage of M. wulii infection. A2M is the most versatile anti-protease and capable of trapping and silencing a variety of classes of proteases (Armstrong, 2006;Alvarez-Pellitero, 2008). Decreased expression of A2M has been previously reported in Lates calcarifer infected with C. irritans (Khoo et al., 2012) and in rainbow trout following an inflammatory stimulus (Freitas-Lopes et al., 2017), evidencing that A2M could act as a negative APP to regulate host or parasites-derived proteases. ...
Article
Liver myxobolosis, caused by Myxobolus wulii severely prevents the sustainable development of gibel carp (Carassius auratus gibelio) aquaculture in China. More insights into the host-parasite interaction will undoubtedly help to develop potential solutions to control this myxobolosis. Liver is an important organ to perform immunological and metabolic functions, changes of gene expression profile involved in fish liver against the local myxosporean infection, however, remain unknown. Here, a comparative transcriptomic analysis of severely infected and mildly infected liver from the same fish individuals, liquefying liver from the just died fish and control liver from the uninfected fish was conducted to investigate the possible involved molecular responses in the liver against the M. wulii infection. Upregulated differentially expressed genes (DEGs) were predominantly involved in adaptive immune responses, including the anti-inflammatory responses resulted from the synergism of Th1, Th17 and Treg cells, and antibody responses mediated by B cells. Downregulated DEGs were mainly involved in metabolic processes. Furthermore, 10 representative DEGs possibly involving in the immune-metabolic interactions were downregulated in the affected liver, demonstrating that the possible synergic mechanism of the suppression of metabolic activities and the facilitation of anti-inflammatory responses occurred in the infected liver. Combining the significant downregulation of cytoskeleton-related genes and upregulation of cell size-related genes, the histopathological, transmission and scanning electron microscopic analysis, it can be suspected that M. wulii is of intracellular infection. This is the first study to elucidate the molecular mechanism of immune-metabolic interactions underlying the fish liver myxobolosis, which will deepen the knowledge of the fish-myxospoean dialogue.
... Greater prevalence of these myxozoans in river-exposed fish contributed to heavier overall infection burdens and richness; continued river exposure if fish were not transported to the laboratory would further increase infective dosage (Benda et al., 2015;Ray et al., 2012). New infectious agents accumulated during river entry may elicit host responses that were not activated for carrier-state infections, and this enhanced response may be deleterious due to cross-reactive immune responses (Alizon et al., 2013;Alvarez-Pellitero, 2008). The demands of osmoregulatory transition and new infections probably reduce the capacity of adult salmon to effectively respond to thermal, fishery, and other stressors, especially given limited endogenous resources (Kiessling et al., 2004). ...
Preprint
Incorporating host-pathogen(s)-environment axes into management and conservation planning is critical to preserving species in a warming climate. However, the role pathogens play in host stress resilience remains largely unexplored in wild animal populations. We experimentally characterized how independent and cumulative stressors (fisheries handling, high water temperature) and natural infections affected the health and longevity of released wild adult sockeye salmon (Oncorhynchus nerka) in British Columbia, Canada. Returning adults were collected before and after entering the Fraser River, yielding marine- and river-collected groups, respectively. Fish were exposed to a mild (seine) or severe (gill net) fishery treatment at collection, and then held in circulating freshwater tanks for up to four weeks at historical (14°C) or projected migration temperatures (18°C). Using weekly nonlethal gill biopsies and high-throughput qPCR, we quantified loads of up to 46 pathogens with host stress and immune gene expression. Marine-captured fish had less severe infections than river-captured fish, a short migration distance (100 km, 5-7 d) that produced profound infection differences. At 14°C, river-collected fish survived 1-2 weeks less than marine-collected fish. All fish held at 18°C died within 4 weeks unless they experienced minimal handling. Gene expression correlated with infections in river-collected fish, while marine-collected fish were more stressor-responsive. Cumulative stressors were detrimental regardless of infections or collection location, likely due to extreme physiological disturbance. Because river-derived infections correlated with single stressor responses, river entry likely decreases stressor resilience of adult salmon by altering both physiological status and pathogen burdens, which redirect host responses toward disease resistance.
... The response of the fish immune system after parasite invasion is variable and reliant on a multitude of factors (fish age, infected organ, class of parasite), with a different outcome in terms of damage extent to host tissues [24,77,78]. ...
Article
Full-text available
Histozoic parasite–fish host interaction is a dynamic process that leads to the formation of a granuloma, a specific chronic inflammatory response with discernible histological features. Mullets (Osteichthyes: Mugilidae) represent a suitable model concerning the development of such lesions in the host–parasite interface. The present work aimed to identify granuloma developmental stages from the early to the late phase of the infection and to characterize the immune cells and non-inflammatory components of the granuloma in different stages. For this purpose, 239 mullets were collected from 4 Sardinian lagoons, and several organs were examined by combining histopathological, bacteriological, and immunohistochemical methods. Granulomas associated with trematode metacercariae and myxozoan parasites were classified into three developmental stages: (1) pre-granuloma stage, characterized by intact encysted parasite and with no or mild tissue reaction; (2) intermediate stage, with partially degenerated parasites, necrosis, and a moderate number of epithelioid cells (ECs); and (3) late stage, with a necrotic core and no detectable parasite with a high number of ECs and fibroblasts. The three-tier staging and the proposed morphological diagnosis make it conceivable that histopathology could be an essential tool to evaluate the granulomas associated with histozoic parasitic infection in fish.
... Respiratory burst is considered as a strong defence response of fish to pathogens. [92][93][94] In the present study, the probiotics had no significant effects on respiratory burst activity according to the results of meta-analysis. This result was inconsistent with the reports of many studies that reported the increasing effects of probiotics on respiratory burst activity. ...
Article
Probiotics are microbial cells with multifunctional properties including immunostimulatory function in their host. Today, probiotics are widely used for controlling diseases in aquaculture, especially for rainbow trout, Oncorhynchus mykiss, as the most important commercial cold-water fish in the world. So far, many studies have been conducted on the effect of probiotics on the immune system of rainbow trout, but due to different experimental conditions, these results are different and sometimes inconsistent. Therefore, the aim of the present study was to perform a systematic review and meta-analysis to eliminate inconsistencies and to clarify the results related to some immune parameters in rainbow trout. This study is the first meta-analysis study of probiotic-induced effects on the immune system of rainbow trout. In order to perform meta-analysis, four Internet databases, PubMed, Scopus, ISI Web of Science and Google Scholar were systematically searched until 27/03/2020 and after receiving related articles, effect sizes related to 10 outcomes including serum and plasma lysozyme activity, ACH50 activity, Ig activity, serum complement activity, phagocytosis activity, serum total protein activity and respiratory burst activity were evaluated by SMD and Hedges' g statistic and 95% CI was calculated from a random effects model. The SYRCL’S risk of bias tool for animal study was also used to assess the quality of the studies. Meta-analysis was performed for 36 studies by 499 experiments. The effect of probiotics on immunity components was as follows: serum lysozyme activity (p < 0.05), plasma lysozyme activity (p > 0.05), Serum ACH50 activity (p < 0.05), Plasma ACH50 activity (p < 0.05), serum immunoglobulin activity (p < 0.05), plasma immunoglobulin activity (p < 0.05), total serum protein activity (p < 0.05), serum complement activity (p < 0.05), phagocytic activity (p < 0.05) and respiratory burst activity (p > 0.05). In conclusion, the results of the present study showed that, except plasma lysozyme activity and burst activity, probiotics could enhance immune system of rainbow trout.
... Parasitic diseases are a concern for the fish industry because they are responsible for lesions that predispose fish to secondary infections and can themselves cause outbreaks of mortality (de Jesus et al., 2018;Ogawa, 2014). Parasites are of increasing importance because fish are routinely subjected to stressful practices that may impair their defence against infections (Alvarez-Pellitero, 2008). The impact of parasitic diseases has increased the interest in improving the immune system and health of farmed fish (Bruce & Brown, 2017;Magnadóttir, 2010). ...
... Among the most relevant limitations to fish aquaculture, infectious diseases represent a very serious concern. Several pathogens, including bacteria (Toranzo et al. 2005), viruses (Crane & Hyatt 2011) and parasites ( Alvarez-Pellitero 2008), affect the health status of farmed fish, causing important economic losses. The emergence of antibiotic-resistant bacteria (Miller & Harbottle 2018) and the absence of effective or safe vaccines and/or treatments against most of the viral, parasitic and fungal diseases affecting fish (Kibenge et al. 2012;Dadar et al. 2017) limit the control and eradication of disease outbreaks. ...
Article
The implementation of antiviral treatments and prophylaxis strategies in fish aquaculture needs to be established. The absence of commercial vaccines for most viral diseases affecting economically relevant fish species, and the total lack of treatments to fight these diseases once they have emerged in a fish farm remains one of the main bottlenecks in fish aquaculture production. However, although no antivirals are currently applied on farms, a great number of investigations have been conducted to assess the potential use of antiviral treatments against several fish viruses. Although most of these works were based on in vitro approaches, some included in vivo experiments to demonstrate the potential applicability of these treatments. This review summarizes the investigations conducted both in vitro and in vivo in the field of antiviral treatments against fish viruses. The highlighted works include those using piscine and non‐piscine proteins with antimicrobial functions, metabolites, chemical compounds (some of which are used in medicine to treat human viruses), bioactive compounds mainly isolated from plants and bacteria, and emerging DNA‐ and RNA‐based therapeutics. This information can be used for developing both specific and broad‐spectrum antiviral strategies to be further used in the aquaculture industry, and it may even provide interesting indications for biomedical research.
... It is a mucolytic enzyme produced by different immune cells such as leukocytes, monocytes, and neutrophils. Its principal function is lysing bacteria; it can activate the complement cascade and the phagocytic process (Alvarez-Pellitero 2008). In this study, catfish infected by Orientocreadium batrachoides had mean lysozyme levels of 250.00-387.00 ...
Article
Full-text available
Parasitic infection may cause massive losses in Clarias gariepinus fries and fingerlings. Therefore, this study aimed to characterize the digenetic trematodes species (two adults’ flukes and one metacercariae) infecting African catfish Clarias gariepinus, as well as their histopathological impacts on infected fish. The intestinal flukes were identified as Orientocreadium batrachoides and Masenia bangweulensis based on their morphological and molecular characteristics. Sequencing of their 28S (LSU rRNA) and 18S rRNA (SSU rRNA) genes confirmed that these trematodes belong to the families Orientocreadiidae and Cephalogonimidae, respectively. The metacercariae trematode infecting skin and muscles were only morphologically identified as Cyanodiplostomum sp. The gene expression levels of MHC II increased in naturally infected fish either with O. batrachoides or Cyanodiplostomum sp. alone, compared with uninfected catfish. In addition, lysozyme levels in individual fish serum increased in catfish infected either with O. batrachoides or Cyanodiplostomum sp. alone. Histopathological examination of the skin revealed embedded parasitic cysts that displaced tissue in the dermis. Surrounding tissues were infiltrated with melanomacrophages and displayed dermal edema. Histopathological analysis showed O. batrachoides or M. bangweulensis between the gastric folds of the stomach of infected catfish, causing infiltration of mononuclear inflammatory cells in the lamina propria.
... Therefore, the hemolytic exertion in fish serum is recognized as an intersperse complement pathway, which plays a vital role against infectious pathogens 55 . In this study, a significant hemolysin titer was obtained with the 4 mg kg −1 CA, suggesting the influence of complement pathways against pathogens 56 . However, the groups fed with a low dose (2 mg kg −1 CA) produced a high hemolysin titre in the later stages, whereas a high dose (8 mg kg −1 CA) produced similar results in the earlier stages. ...
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The effect of chrysophanic acid (CA) (2, 4, and 8 mg kg-1) on the immunity and immune-related gene profile of Catla catla against Aeromonas hydrophila is reported. In both control and treated groups fed with 2 mg kg-1 (2 CA), the phagocytosis, hemolytic, myeloperoxidase content, and superoxide anion production decreased significantly between sixth and eighth weeks, whereas when fed with 4 mg kg-1 CA (4 CA) the H2O2 production and nitric oxide synthase increased significantly between fourth and eighth week. When fed with 2 CA and 4 CA diets, the total protein, bactericidal, and antibody titer increased significantly from the fourth week onwards. When fed with 2 CA, the IL-1β and IL-10 mRNA expression of head kidney leucocytes were significant between weeks six and eight. The expressions of toll-like receptors significantly increased when fed with a 4 CA diet from fourth week onwards. The 4 CA group significantly increased in TNF-α, TNF receptor-associated factor 6 (NOD), which influences protein expression, after the fourth week. The mRNA transcription of MHCI, lysozyme-chicken and goose type expressions significantly increased in 4 CA group within the fourth week. In summary, the dietary administration of 4 mg kg-1 of CA (4 CA) provides better immunity and enhances the up-regulation of immune-related genes in Catla against A. hydrophila.
... One unit of SOD was defined as the amount of protein that inhibits in 50% the auto-oxidation rate of pyrogallol at 25 • C, pH 8.2 in a minute. The SOD activity was expressed in units per mL of sample (U/mL) [20]. ...
Article
Growth Hormone-Releasing Peptide 6 (GHRP-6) (His-(D-Trp)-Ala-Trp-(D-Phe)-Lys-NH2) is an agonist of the growth hormone secretagogue receptor. GHRP-6 mimics the effect of ghrelin. The present study focuses on the immunomodulatory effects of GHRP-6 in tilapia with and without the presence of Pseudomonas aeruginosa infection. GHRP-6 up-regulated the transcription levels of three piscidin-like antimicrobial peptides (Oreochromicins I, II, and III) and granzyme in a tissue-dependent manner. Antimicrobial activity stimulation in serum (lysozyme and anti-protease activity) was also confirmed. Besides, GHRP-6 enhanced the in vitro antimicrobial activity against P. aeruginosa in tilapia gills mucus and serum samples and decreased the bacterial load in vivo after infection with this Gram-negative bacterium. Our results evidenced, for the first time, a direct link between a growth hormone secretagogue ghrelin mimetic in fish and the enhancement of antimicrobial peptides transcription, which suggests that this secretagogue is capable to lead the activation of microbicidal activity in tilapia. Thus, these results open new possibilities for GHRP-6 application in aquaculture to stimulate the teleost immune system as an alternative treatment against opportunistic bacteria.
... Nevertheless, an adaptive immunity has also been described in teleost, made of T and B lymphocytes, together with a cytokine network and a production of specific antibodies. However, the adaptive immune response has been described as slower than that of mammals, with a more limited repertoire, where specific antibodies are not detected until three or four weeks after immunization, thus making it a less efficient response than the one described for mammals [13,20]. ...
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Piscirickettsia salmonis, the etiological agent of the Salmon Rickettsial Septicemia (SRS), is one the most serious health problems for the Chilean salmon industry. Typical antimicrobial strategies used against P. salmonis include antibiotics and vaccines, but these applications have largely failed. A few years ago, the first attenuated-live vaccine against SRS (ALPHA JECT LiVac® SRS vaccine) was released to the market. However, there is no data about the agents involved in the activation of the immune response induced under field conditions. Therefore, in this study we evaluated the expression profile of a set of gene markers related to innate and adaptive immunity in the context of a cellular response in Atlantic salmon (Salmo salar) reared under productive farm conditions and immunized with a live-attenuated vaccine against P. salmonis. We analyzed the expression at zero, 5-, 15- and 45-days post-vaccination (dpv). Our results reveal that the administration of the attenuated live SRS LiVac vaccine induces a short-term upregulation of the cellular-mediated immune response at 5 dpv modulated by the upregulation of ifnα, ifnγ, and the cd4 and cd8α T cell surface markers. In addition, we also registered the upregulation of il-10 and tgfβ. Altogether, the results suggest that a balanced activation of the immune response took place only at early times post-vaccination (5 dpv). The scope of this short-term upregulation of the cellular-mediated immune response against a natural outbreak in fish subjected to productive farm conditions deserves further research.
... Toxins or enzymes released by the parasites might have damaged the leucopoietic system resulting in reduction in the expression of most of the immune-related genes, including tnf-α (Kar et al., 2015). However, functionally assessed to have pro-inflammatory activity in fish, il-1β and tnf-α are often co-expressed with other macrophage-derived inflammatory mediators such as il-8, cox-2, and inos in parasitic and bacterial infestations (Harun et al., 2011;Bruijn et al., 2012;Oladiran et al., 2011;Alvarez-Pellitero, 2008;Covello et al., 2009). Some cytokine genes were mainly down regulated including TNF-α, an important proinflammatory cytokine in fish (Sigh et al., 2004a(Sigh et al., , 2004b. ...
Article
The ectoparasite protozoan Amyloodinium ocellatum (AO) is the causative agent of amyloodiniosis in European seabass (ESB, Dicentrarchus labrax). There is a lack of information about basic molecular immune response mechanisms of ESB during AO infestation. Therefore, to compare gene expression between experimental AO-infested ESB tissues and uninfested ESB tissues (gills and head kidney) RNA-seq was adopted. The RNA-seq revealed multiple differentially expressed genes (DEG), namely 679 upregulated genes and 360 downregulated genes in the gills, and 206 upregulated genes and 170 downregulated genes in head kidney. In gills, genes related to the immune system (perforin, CC1) and protein binding were upregulated. Several genes involved in IFN related pathways were upregulated in the head kidney. Subsequently, to validate the DEG from amyloodiniosis, 26 ESB (mean weight 14 g) per tank in triplicate were bath challenged for 2 h with AO (3.5 × 10⁶/tank; 70 dinospores/ml) under controlled conditions (26-28 °C and 34‰ salinity). As a control group (non-infested), 26 ESB per tank in triplicate were also used. Changes in the expression of innate immune genes in gills and head kidney at 2, 3, 5, 7 and 23 dpi were analysed using real-time PCR. The results indicated that the expression of cytokines (CC1, IL-8) and antimicrobial peptide (Hep) were strongly stimulated and reached a peak at 5 dpi in the early infestation stage, followed by a gradual reduction in the recovery stage (23 dpi). Noticeably, the immunoglobulin (IgM) expression was higher at 23 dpi compared to 7 dpi. Furthermore, in-situ hybridization showed positive signals of CC1 mRNA in AO infested gills compared to the control group. Altogether, chemokines were involved in the immune process under AO infestation and this evidence allows a better understanding of the immune response in European seabass during amyloodiniosis.
... Currently, among the most prominent limitations to the further development of aquaculture is the prevalence of infectious diseases, with pathogenic bacteria (Toranzo et al., 2005), viruses (Crane and Hyatt, 2011), and parasites (Alvarez-Pellitero, 2008), potentially compromising the health status of farmed fish, and thereby causing important economic losses. This is notably evident in the case of marine aquaculture species that are exposed to the open-ocean environment, for which disease prevention through management and biosecurity is particularly challenging (Lafferty et al., 2015). ...
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Genomic selection is effective in enhancing the selection efficiency during breeding for improved disease resistance in fish. However, given that the collection of routine disease challenge data is generally costly and that disease resistance traits are threshold traits with typically low heritability, there has been comparatively limited progress in improving the accuracy of genomic prediction. The objective of this study was to assess the advantage of a multiple-trait linear-threshold model in genomic prediction of disease resistance traits in fish. The study was based on analyses of both simulated data and real data obtained for a rainbow trout population. We simulated a linear trait (growth trait, h² = 0.3) and a binary threshold trait (disease resistance trait, h² = 0.1) with different genetic correlations (0.1, 0.3 and 0.5). Single- and multiple-trait models with best linear unbiased prediction (BLUP) and genomic BLUP (GBLUP) were implemented to investigate their prediction abilities. Moreover, we also assessed the impact of missing proportions of a reference population on genomic prediction for disease resistance traits. The results revealed that methods using marker information produced more accurate predictions than the pedigree-based BLUP method. Furthermore, for between-trait genetic correlations of 0.1, 0.3 and 0.5, the multiple-trait GBLUP for disease resistance traits showed 1.0%, 1.5% and 6.4% higher accuracy than single-trait GBLUP, respectively. Meanwhile, no improvement in accuracy was observed for the assessed growth trait. Moreover, with an increase in the genetic correlation between traits, we observed reductions in the consistency of estimated SNP effects using single-trait and multiple-trait GBLUP models. Our findings indicated the superiority of multiple-trait models in genomic prediction for a disease resistance trait with missing data; this superiority is more pronounced when the proportion of the reference population missing is large. Furthermore, using real data obtained for rainbow trout, we verified the advantage of the multiple-trait linear-threshold model in genomic prediction of binary survival, with the multiple-trait GBLUP model yielding a lower mean squared (absolute) error than the single-trait GBLUP model. Overall, our findings have important implications with regard to applying multiple-trait linear-threshold model in genomic selection for disease resistance in most aquaculture species.
... Vertebrate hosts respond to parasitic infections by generating antibodies, which are effector molecules of humoral immunity. Antibody-mediated immune response plays a critical role during many parasitic infections to protect, clear parasite or to confer resistance to fish [45]. Antiparasite antibodies have been reported in fish during certain parasitic infections such as Bothriocephalus acheilognathi [46], Trypanosoma sp. ...
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Tetracapsuloides bryosalmonae, a myxozoan endoparasite often causes chronic infection in brown trout. Antiparasite immunity mediated by antibodies and B cells is known as an important determinant of host survival and parasite proliferation during chronic infections. Accordingly, studying their time course during proliferative kidney disease (PKD) might be helpful in improving our understanding of its chronic nature. Therefore, we conducted this study to examine parasite specific serum antibody and B-cell-mediated response in laboratory-infected brown trout at different time points. Brown trout were exposed to the spores of T. bryosalmonae, derived from infected bryozoans. Samples were collected at different time points and processed for indirect ELISA, histopathology, and qRT-PCR. T. bryosalmonae specific antibody was detected at 4 weeks post exposure (wpe) and it persisted until 17 wpe. Additionally, the expressions of C4A, CD34, CD79A, BLNK, CD74, BCL7, and CD22 were differentially regulated in the important immune organs, kidney and spleen. To our knowledge, this is the first study addressing anti-T. bryosalmonae antibody response in brown trout at different time points. The results from this study provide valuable insights into the processes leading to changes in B cell development, inflammation and antibody production during the course of PKD in brown trout.
... This can be seen in the FAO (2010) report where it was recorded that the total death proportion in the Scottish Salmon industry (Scotland) dropped from 38% in 1997 to 12% in 2000 with a further decline very recently as a result of sophisticated technological advancements. The quest to find the perfect vaccine started a few decades ago and now molecular tools and technology have progressed in mitigating treatment resistance to some diseases such as sea lice in Atlantic salmon (Alvarez-Pellitero, 2008;OlE, 2001). Recent investigations have concentrated on vaccines contrary to virus-related infections by means of other innovative technology such as peptides, RNA and DNA (Costello, 2009). ...
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This article examines the state of Catfish production in Nigeria and the roles technology has played over the past decades. Heightened demand as a result of increased population puts considerable pressure on production. In response to this pressure aquaculturists ramped up production activities, this demand-driven increase exposes the major gaps as the industry struggles to cope with the absence of fundamental structures like inadequate structured funding, markets, processing and preservation facilities among others. Such gaps exist in all aspects of aquaculture and technology is a viable plug for many of them. The aquaculture of developing nations has certain peculiarities which predispose it to slow development. Many fishermen and aquaculturists in low-income regions are trapped in economic systems that result in relative poverty. Many reasons have been put forward to explain the dynamics behind these consequences with technology playing a major role from the consensus. Rapid advances in hatchery, water quality and molecular technology have been identified as some of the active drivers of Catfish production in Nigeria. The article focuses on the history, progress and prospects of aquaculture technology in Nigeria. It does so by reviewing the technologies already established in Catfish farming and the impact of their roles in balancing fish demand and supply.
... Молекулярна мімікрія, як вид протиімунного захисту паразита, полягає в тому, що паразит укритий речовинами, що кінетичні з білками хазяїна, завдяки чому досить часто не розпізнається факторами імунної системи хазяїна (Van Riet et al., 2007). Але слід зазначити, що навіть за присутності антигенної мімікрії у паразитів, що проникають до тканин хазяїна, та відносну імунологічну толерантність, цисти такими властивостями не володіють, тому сприймаються організмом риб як ксеноген-вальні процеси (Jones, 2001;Alvarez-Pellitero, 2008). ...
Article
This article presents the results of an analysis of the formation and functioning of the «parasite-host» system, as well as its constituent elements, on the example of goby fish (Gobiidae) and trematodes of the Heterophyidae family. The research work consisted of separate stages: determine the distribution of the causative agent of cryptocotylosis among goby fish in a natural reservoir, study clinical signs during this parasitic disease; conduct an experimental invasion of research ducklings in order to determine the pathogenic effects on the bird organism and study the morphology of the mature parasite. The main stages of cryptocotylosis pathogen life cycle were outlined. The distribution of this parasite in the Dnieper-Bug estuary water area and part of the Black Sea in the Nikolaev and Odessa regions was established. It was noted that the parasitic trematode strategy and shared co-evolution led to the appearance, during evolution, of adaptations that balance the dynamic interaction between the parasite and its host: anatomical and morphological characteristics, antigenic mimicry, physiological and trophic characteristics of the parasitic way of being, etc. We also present an analysis of the Heterophyidae families’ trematode behavioral characteristics at different stages of development: eggs, sporocysts, miracidia, cercaria, metacercaria and daydreaming – are mature individuals. Trematode’s adaptive abilities appear already in the early stages of its life cycle. According to the results of experimental invasion of research ducklings, the pathogenic effect of the cryptocotylosis causative agent on the bird organism as the definitive host was established. While determining features of the parasites pathological effect on the organism of experimental ducklings, we recorded inflammatory processes in the intestines of birds: enteritis of varying severity, secondary lesions of the hepatobiliary system. The influence of the parasite on the host organism is not limited only to changes at the organ level. Non-specific protection is manifested mainly through the development of inflammatory reactions at the cellular and humoral levels. A retrospective literature analysis on the basic principles of the “parasite-host” interaction system was also carried out.
... Recently, assessment of fish molecular expression is essential either to investigate the alterations induced by the toxicants (Shen et al., 2020;Vasamsetti et al., 2021;Mahboub et al., 2022a) or the beneficial role of a natural extract (Mahboub et al., 2022b,c). Also, gene expression reflects fish immunological status by involving some mediators for the adaptive and innate responses, i.e., cytokines (IL-6 and TNF-α), (Alvarez-Pellitero, 2008). Herein, we report altered immune-related gene expression in the exposed group to NP reflected by down-regulation of IL-6 and TNF-α genes which verified the NP-induced immuno-toxicity. ...
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Nonylphenol (NP) is a common toxicant that constitutes a potential hazard to the aquatic system. This study assessed the protective role of Salvia officinalis leaves powder (SOLP) against NP toxicity. We addressed mor-talities, growth retardation, hepato-renal dysfunction, immune-antioxidant suppression, histopathological degeneration, and gene down-regulation induced by NP-toxicity. And the potential activity of SOLP against these negative impacts in Mirror carp (Cyprinus carpio var specularis). Acute toxicity assay (static 96-h) was primarily performed to investigate the 96-h LC50 of NP in C. carpio and it was recorded at 1.01 mg/L reckoned by Finney probit analysis. Fish (N = 240) were assigned to 4 treatments for 2 months. The first (control) and the second (SOLP) groups were fed on basal diets that were enriched with 0.0 and 4 g/kg of diet SOLP without NP exposure. The third (NP) and fourth (SOLP+NP) groups were provided with the same diets plus exposed to 1/10 of the 96 h-LC50 of NP (0.1 mg/L). The outcomes revealed that NP induced higher mortalities (46), significantly (p < 0.05) reduced growth, serum immune (nitric oxide and immunoglobulin M), and antioxidants (glutathione peroxidase and catalase) values. Moreover, down-regulation of immune-related genes (interleukin 6 and tumor necrosis factor-alpha) in the head kidney, and gills was observed in the NP group. However, noticeable augmented levels of serum oxidant (malondialdehyde), liver enzymes (Alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase); and kidney biomarkers (creatinine and urea) were recorded in NP group. Extensive pathology revealed that NP induced damage to hepatocytes and renal epithelium and mononuclear cells infiltrations in hepato-renal tissues. Dietary intervention with SOLP reduced mortalities (20 %), restored the reduction in the growth and biochemical indicators, and recovered the histopathology, and gene down-regulation produced by NP. Accordingly, the current study recommended SOLP as a valuable dietary additive in aquaculture owing to its mitigating impacts against NP by improving growth and immune-antioxidant status and regenerating the histological structure with a better gene expression.
... Timely removal of infected/damaged cells is essential for reducing inflammation [76]. However, apoptosis also can be an immune evasion mechanism of pathogens [77,78]. Some parasites have been reported to modulate host apoptosis pathways to their advantage-promoting apoptosis in host immune cells programmed to attack them, which may contribute to the parasite pathogenesis [79,80]. ...
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The dinoflagellate Amyloodinium ocellatum is an important pathogenic parasite infecting cultured marine and brackish water fishes worldwide. This includes cultured Florida pompano (Trachinotus carolinus), which is one of the most desirable marine food fish with high economic value in the USA. A. ocellatum infects fish gills and causes tissue damage, increased respiratory rate, reduced appetite, and mortality, especially in closed aquaculture systems. This study mimicked the natural infection of A. ocellatum in cultured pompano and conducted a transcriptomic comparison of gene expression in the gills of control and A. ocellatum infected fish to explore the molecular mechanisms of infection. RNA-seq data revealed 604 differentially expressed genes in the infected fish gills. The immunoglobulin genes (including IgM/T) augmentation and IL1 inflammation suppression were detected after infection. Genes involved in reactive oxygen species mediating parasite killing were also highly induced. However, excessive oxidants have been linked to oxidative tissue damage and apoptosis. Correspondingly, widespread down-regulation of collagen genes and growth factor deprivation indicated impaired tissue repair, and meanwhile the key executor of apoptosis, caspase-3 was highly expressed (25.02-fold) in infected fish. The infection also influenced the respiratory gas sensing and transport genes and established hypoxic conditions in the gill tissue. Additionally, food intake and lipid metabolism were also affected. Our work provides the first transcriptome sequencing of Florida pompano and provides key insights into the acute pathogenesis of A. ocellatum. This information can be utilized for designing optimal disease surveillance strategies, future selection for host resistance, and development of novel therapeutic measures.
... In our study, as in other studies, the il1b expression levels were up-regulated in the gills and HK upon C. irritans infection [7,48]. In addition, il1b can act as an inducer of other cytokines with pro-inflammatory and chemotactic functions, such as il8 [13]. In our study il8 gene expression was strongly up-regulated in both the gills and in the HK during C. irritans infection, something that also occurs in grouper undergoing C. irritans infection [7]. ...
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The protozoan parasite Cryptocaryon irritans causes marine white spot disease in a wide range of fish hosts, including gilthead seabream, a very sensitive species with great economic importance in the Mediterranean area. Thus, we aimed to evaluate the immunity of gilthead seabream after a severe natural outbreak of C. irritans. Morphological alterations and immune cell appearance in the gills were studied by light microscopy and immunohistochemical staining. The expression of several immune-related genes in the gills and head kidney were studied by qPCR, including inflammatory and immune cell markers, antimicrobial peptides (AMP), and cell-mediated cytotoxicity (CMC) molecules. Serum humoral innate immune activities were also assayed. Fish mortality reached 100% 8 days after the appearance of the C. irritans episode. Gill filaments were engrossed and packed without any space between filaments and included parasites and large numbers of undifferentiated and immune cells, namely acidophilic granulocytes. Our data suggest leukocyte mobilization from the head kidney, while the gills show the up-regulated transcription of inflammatory, AMPs, and CMC-related molecules. Meanwhile, only serum bactericidal activity was increased upon infection. A potent local innate immune response in the gills, probably orchestrated by AMPs and CMC, is triggered by a severe natural outbreak of C. irritans.
... The spleen and gill are important immune organs in fish. The spleen is the primary hematopoietic and peripheral lymphoid organ (16,17) and is important for antigen (e.g., bacteria) presentation and initiation of adaptive immune responses (18,19). The gill is a type of mucosal surface and a mucosal immune organ in fish (14,20), and is an important site of bacterial exposure and host defense mechanisms (14). ...
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Takifugu rubripes is commonly subjected to the disease-causing bacterium, Vibrio harveyi . However, the mechanism involved in the immune response of T. rubripes to V. harveyi infection is unclear. We conducted a transcriptomic analysis of the spleen and gill from T. rubripes infected with V. harveyi . We obtained 60,981,357 and 60,760,550 clean reads from the control and infected spleens, and 57,407,586 and 57,536,651 clean reads from the control and infected gills, respectively. We also identified 1,560 and 1,213 differentially expressed genes in the spleen and gill, respectively. Gene ontology analysis revealed that the most enriched biological process in both the spleen and gill was “immune response”. The most enriched Kyoto Encyclopedia of Genes and Genomes immune response–related pathways were the NOD-like receptor signaling pathway in the spleen and cytokine–cytokine receptor interaction in the gill. We found 10 candidate immune-related genes in the spleen and gill. These putative immune pathways and candidate genes will provide insight into the immune response mechanisms of T. rubripes against V. harveyi .
... Non Commercial Use and Sahoo, 2008;Boshra et al., 2006;Alvarez et al., 2008) while as defense against repetitive afflictions is overseen by adaptive immunity. The latter reaction being brought about by B and T lymphocytes and antibodies. ...
... Fish skin is a major barrier to the harmful agents in exterior environment, which is possible due to the skin's complex structure and cell composition (Ostrander, 2000). The skin mucus is a composite of defensive molecules, including mucins together with factors of both the innate and adaptive immune system (Alvarezpellitero, 2008). ...
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The gene encoding HSP70 was isolated from Microptenus salmoides by homologous cloning and rapid amplification of cDNA ends (RACE). The HSP70 transcripts were 2116 bp long and contained 1953 open reading frames encoding proteins of 650 amino acids with a molecular mass of 71.2 kDa and theoretical isoelectric point of 5.22. The qRT-PCR analysis showed that the HSP70 gene was differentially expressed in various tissues under normal conditions, and the highest HSP70 level was observed in the spleen and the lowest levels in the muscle and heart. The clear time-dependent expression level of HSP70 was observed after bacterial challenge and heat stress. A significant increase in HSP70 expression level was detected and reached a maximum at 3 h and 6 h in liver, spleens and gill tissues after Aeromonas hydrophila infection and heat stress, respectively (P < 0.05). As time progressed, the expression of HSP70 transcript was downregulated and mostly dropped back to the original level at 48 h. The concentration of cortisol, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) increased as the time of stress progressed, with the highest level found on 3 h and later declined rapidly and reached to the control levels at the 48 h. Those results suggested that HSP70 was involved in the immune response to bacterial challenge and heat stress. The cloning and expression analysis of the HSP70 provide theoretical basis to further study the mechanism of anti-adverseness in Microptenus salmoides.
Article
Intensive fish production has arguably resulted in a consequential increase in the incidence of disease within the aquaculture industry. The frequency and the severity of disease events are in part affected by changing global climatic conditions. More importantly, these changes directly influence changes in water quality parameters and the dynamics of a microbiome, pathogenic or not, in aquatic farming. Changes in temperature, for example, have both direct and indirect effects on the health status of fish, potentially increasing their predisposition to infections. In general terms, fish infections are rarely caused by a single agent or factor-frequently, multiple pathogens, changes in water quality parameters, production factors (e.g. feed quality , stocking density) and host immunity are concomitantly responsible for the establishment of infections in fish farms. Ciliate protozoans represent an important microfauna in aquatic environments. Ciliated protozoans can proliferate quickly, debilitating the host, and, in the absence of an intervention, can lead to a significant loss of stock. Ciliate infections frequently facilitate the establishment of secondary microbial species, both of which are linked to environmental and culture conditions. In this review, economically important ciliated protozoans of warm-water cultured fish and their potential interactions with their associated bacterial micro-biomes (both on/in their hosts and their surrounding environment) are discussed. Also, potential environmental triggers behind ciliate outbreaks within warm-water aquaculture are reviewed. With better knowledge about such interactions, it will be possible to highlight innovative strategies to control ciliate parasites and bacterial infections in aquaculture.
Article
A parasitic survey was performed during July 2017 to February 2018 to emphasize the prevalence and spatial distribution of ectoparasites in Mystus vittatus from three sampling sites of River Penna flowing through YSR District, Andhra Pradesh by routine parasitological procedures. A total of 238 ectoparasites were obtained from the gills of 70 examined fishes with a prevalence of 77.1%, mean intensity of 4.4 and mean abundance of 3.4 respectively. Three species of ectoparasites i.e., two monogeneans—Cornudiscoides vittati (n = 119); Bifurcohaptor indicus (n = 90) and one copepod, Lamproglena hospetensis (n = 29) were obtained from the gills of the host. All the 3 species of gill ectoparasites showed an aggregated distribution pattern (2.92, 2.52 and 2.83). Only, B. indicus showed a significant positive relationship between the condition factor and parasitic abundance (rs = 0.361, p = 0.0021) followed by C. vittati (rs = 0.206, p = 0.086) whereas the parasitic abundance of L. hospetensis (rs = − 0.213, p = 0.076) showed a weak negative correlation with the relative condition factor of the host. Parasitization was analyzed location wise and fishes collected from Site-I (Mylavaram) were highly infected with both the monogeneans while parasitization with copepods was nil. However, the parasitization of copepods was relatively higher in Site-II (Chennur). There was no influence of host size and host sex on the parasitization and also no specific preference for the sides of the fish host. The monogeneans segregated the niche to prevent resource competition i.e., C. vittati and L. hospetensis were prevalent in gill arches II and I respectively whereas B. indicus occupied gill arch III. Both the monogeneans showed very a high interspecific association (rj = 0.96) with each other but showed a very negligible association with L. hospetensis. This type of study will help the aquaculturists to implement many advanced management strategies in aquaculture and improve the yield of Mystus vittatus in the Southern states of India.
Thesis
Blunt snout bream (BSB), Megalobrama amblycephala, is a herbivorous freshwater fish native to China and a major aquaculture species in Chinese freshwater polyculture systems. Recently, the bacterium Aeromonas hydrophila has been reported to be its pathogen causing hemorrhagic septicemia clinical signs and great great ecomomic losses of farmed BSB. This study used next generation sequencing technology to better comprehensive the transcriptome profiles of response-related genes in the BSB which will facilitate further research into the resistance and susceptibility of this fish species to exogenously invasive pathogens. The data analysis of transcriptome profile and expression of immune-related genes from BSB upon A. hydrophila stimulation was also described. The main results are as follows: 1. As an initial step, the pathogenicity of A. hydrophila to BSB was carried out to confirm whether A. hydrophila is a main pathogen causing hemorrhagic septicemia in BSB. The fish was challenged with bacterial concentrations of 1.7×105, 1.7×106, 1.7×107 and 1.7×108 cfu/mL for 7 days post infection. The results showed that mortality was bacterial-dose dependent, with 100% mortality observed at day 1 at the highest dose (1.7×108 cfu/mL). Control fish exhibited cumulative mortalities of 0%. The median lethal dose (LD50) was 5×106 cfu/mL. A total of 15 Aeromonas strains were re-isolated from challenged fish and re-identified based on morphological characteristics, biochemical tests and genomic DNA gene sequencing. No bacteria were isolated from the control group. This study results indicated that A. hydrophila is capable of causing hemorrhagic septicemia in BSB. Moreover, antibiotic susceptibility test with two strains D4 and HU201301 was investigated; the results showed that both strains were sensitive to most of the tested antibiotic drugs. 2. To understand the immune response of the BSB to A. hydrophila infection, the RNA-Seq technology was utilized to analyze the transcriptomic profile after artificial bacterial infection. Two cDNA libraries synthesized from tissues collected from control BSB or those injected with A. hydrophila were sequenced by using Illumina HiSeq2000. After de novo assembly, 155,052 unigenes (average length 692.8 bp) were isolated. All unigenes were annotated using BLASTX relative to several public databases. The sequence similarity (86%) of the assembled unigenes was to zebrafish based on the Nr database. A number of unigenes (n = 30,482) were assigned to three GO categories: biological processes (25,242 unigenes), molecular functions (26,096 unigenes), and cellular components (22,778 unigenes). 20,909 unigenes were classified into 25 KOG categories and 28,744 unigenes were assigned to 315 specific signaling pathways. In total, 238 significantly differentially expressed unigenes (mapped to 125 genes) were identified: 101 upregulated genes and 24 downregulated genes. Another 303 unigenes were mapped to unknown or novel genes. Among the known expressed genes identified, 53 were immune-related genes and were distributed in 71 signaling pathways. 3. Microsatellites (n = 10,877), including di- to pentanucleotide repeat motifs, were also identified in the BSB transcriptome profiles. Dinucleotide repeats were most common (7,152, 65.8%), followed by tri- (3,172, 29.2%), tetra- (549, 5.05%), and pentanucleotide repeat motifs (4, 0.04%). The lengths of the SSRs ranged from 12 to 25 bp. PCR primers were successfully designed for 5077 (46.7%) of the identified microsatellites. Furthermore, a total of 36,326 putative SNPs were discovered from the transcripts. The frequency of SNP was one SNP in 29.2 bp sequence length. The transition and transversion mutation was 21,445 and 12,553 SNPs, respectively. A ratio of transition to transversion was 1.71. Within those yielded SNPs, 10,812 SNPs identified from 2,421 unigenes could be annotated to differential functionality in comparing to public database using BLASTX for GO, KOG and KEGG. A number of SNPs (n = 7,727, 71.5%) found from 1,628 unigenes were assigned to three main GO categories: ‘cellular components’, ‘molecular function’ and ‘biology process’. In total, 5,812 (53.8%) SNPs identified from 1,324 unigenes were classified into 25 KOG categories. 4,589 (42.4%) SNPs detected from 975 unigenes were assigned to 278 KEGG pathways. Furthermore, a number of 600 SNPs found from 111 unigenes were successfully annotated to the term ‘immune system’ via KEGG classification. The database could be useful for further genetic studies in BSB. 4. In silico characterization and homology modeling of encoded proteins, including MaTLR5, MaNFKBIA, MaMyD88, MaTRAF6, MaC3, MaC7, MaCTSL, MaMMP-9, MaIL-8 and MaIL-10 in BSB were performed. Physicochemical and functional characteristics of proteins were analyzed. The secondary and tertiary of the protein’s domains were constructed applying the comparative modeling method. 5. Reverse transcription–quantitative PCR (RT–qPCR) was used to analyze the expression of immune-related genes (MaTLR5, MaNFKBIA, MaMyD88, MaTRAF6, MaC3, MaC7, MaCTSL, MaMMP-9, MaIL-8, and MaIL-10) in response to A. hydrophila. The results showed that all investigated genes were highly up- or and downregulated in the liver, spleen and kidney during the challenge time from 4 to 120 hours post injection. This research provides the important roles of these genes in the BSB’s innate immune system. The results provide significant valuable information of molecular data, which are useful for further study of the immunogenetics of BSB.
Chapter
Globally, incidences of fish diseases caused by parasites have been on a rise, especially in intensive aquaculture practise, leading to considerable economic losses. The traditional control measures and therapeutics used to manage parasitic infections are associated with numerous limitations as well as risks. Vaccines have emerged as an effective means for control of pathogens; the use of vaccines for bacterial fish diseases has successfully cut down the use of antibiotics in aquaculture. However, development of vaccines for parasitic diseases of fish has seen limited success with availability of only commercial vaccine against sea lice. Nevertheless, significant strides have been made in understanding host-parasite interactions, which provides researchers with the arsenal of information required for identification of vaccine candidates and their development. In this review, we discuss protective responses reported in fish against major group of parasites and various efforts made in the field of vaccine development for important parasite groups of both marine and freshwater fish.
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This study was carried out to profile key characteristics of intestinal functions and health in wild-caught Ballan wrasse. To describe functional variation along the intestine, samples were collected from four intestinal segments, named from the proximal to the distal segment: IN1, IN2, IN3 and IN4. The sections showed quite similar structure, i.e. regarding mucosal fold height and branching, lamina propria and submucosal width and cellular composition and thickness of the muscle layers. Leucine aminopeptidase and maltase capacity decreased from IN1 to IN4, suggesting a predominant role of IN1 in digestion. Gene expression levels of vitamin C transporter (slc23a1) and fatty acid transporters (cd36 and fabp2) were higher in IN1 than in IN4, indicating a more important role of the proximal intestine regarding transport of vitamins and fatty acids. Higher expression of the gene coding for IgM heavy chain constant region (ighm) was found in IN4 than in IN1, suggesting an important immune function of the distal intestine. Other immune related genes il1b, il6, cd40, showed similar expression in the proximal and the distal part of the intestine. Parasite infection, especially the myxozoan parasite Enteromyxum leei, coincided with infiltration of lymphocytic and eosinophilic granular cells in the submucosa and lamina propria. The present study established reference information necessary for interpretation of results of studies of intestinal functions and health in cultured Ballan wrasse.
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The structural response and plasticity of the cestode tegument in response to the influence of the host organism is not yet well understood. The main aims of our in vitro study were to analyse the ultrastructural mechanisms and kinetics of tegumental secretion in two cestode species, Dibothriocephalus dendriticus and Ligula interrupta, in response to the influence of fish host blood serum. The incubation of plerocercoids in the culture medium, which contained fish host blood serum, resulted in an increased number of secretory products on the tegumental surface. Our study is the first to experimentally demonstrate the formation of plerocercoid protective layers influenced by the host's internal environment factors. The mechanism of the generation of the protective layer included the following: the intensive formation of organelles in the tegumental cytons and their transfer to the distal cytoplasm of the tegument; increases in extracellular vesicles and vacuoles released on the tegumental surface; arrangement of secretory products and fine‐dispersed extracellular matrix in layers; and formation of the protective layer. The structural tegumental response included increases in the glycocalyx layer and structural changes. Our study revealed that the universal mechanism of protective layer formation was intrinsic to different tapeworms. We hypothesize that plerocercoids of cestodes parasitizing fish may use tegumental secretion in the formation of a protective layer and in the release of immunoregulator molecules to evade the host's immune response.
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In our study, we obtained new data on the leukocyte composition of the spleen of Siberian roach and goldfish infected with Ligula interrupta and Ligula intestinalis, respectively, in a comparative aspect. The sample of fish consisted of non-aquatic catches, the same size-age composition (age + 3 ... + 5, body length 145–237 and 150–180 mm, respectively, weight – 100–184 and 120–174 g) from water bodies of the Baikal lake basin (Dolgoye lake, Cheremukhovoye, Gusinoye). It is noted that in the spleen of goldfish the number of lymphocytes did not change in general, but there was a significant change in the ratio of mature and immature forms: the number of prolymphocytes decreased by 1.5 times, and the content of mature lymphocytes increased by 3.8 times. Unlike goldfish, the infected roach showed the formation of vacuolated cells up to 5.3%, and intense leukopoiesis processes are observed, which is confirmed by a higher content of blasts (by 3 times). Among the granulocytic reactions in fish, similar reactions were observed along the line of neutrophils: a significant increase in poorly differentiated forms in goldfish, as well as mature microphages in roach. It has been shown that, in these parasitic systems, ligulid larvae can be modulators of the adaptive immune response.
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Heat shock proteins (HSPs) play a key role in anti-stress and immune processes and are associated with autoimmune diseases. In order to explore the immunological role of HSPs from Schizothorax prenanti (S. prenanti), SpHSP60 was cloned for the first time in this study, and the gene expressions of SpHSP27, SpHSP60, SpHSP70 and SpHSP90 in the hepatopancreas, head kidney, hindgut and spleen were analyzed by quantitative real-time PCR (qPCR) after treatment with lipopolysaccharide (LPS). The open reading frame of the SpHSP60 gene (GenBank accession number ON245159) is 1728 bp. It encodes a protein of 575 amino acids. Its C-terminus is a highly conserved and repeated glycine sequence, which is an important cofactor in ATP binding. Compared with the control group, most of the SpHSPs were significantly upregulated in the tissues examined at 12 or 24 h after LPS challenge. The most abundant expression of SpHSP70 was found in the head kidney at 24 h after LPS injection, followed by SpHSP27 in the spleen at 24 h; both of these SpHSPs displayed strong expression under the LPS stresses, about 20–70 fold more than that of SpHSP60 and SpHSP90. The temporal expression patterns of the four SpHSP genes were different in the four tissues examined. Taken together, the results suggest that SpHSP27, SpHSP60, SpHSP70 and SpHSP90 participate in innate immunity stimulated by LPS, and the response intensity of the SpHSPs was organ-specific, indicating they could provide early warning information against bacterial infection. The findings in our study will contribute to better understanding the biological processes and important roles of SpHSPs involved in defending against pathogenic bacterial challenge.
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Cryptocaryon irritans is one of the most important ectoparasites of marine fish, and can have a devastating effect on aquacultured fish populations. The role of TLR signaling pathways in anti-parasitic immune responses is poorly understood in fish. In this paper, we first cloned Epinephelus coioidesMyD88 full-length cDNA (EcMyD88) and its respective gene. The open reading frame (ORF) of cDNA is 873 bp encoding 291 amino acid residues. Similar to other species, the EcMyD88 gene contains of five conserved exons and four diverse introns. The constitutive expression of EcMyD88 was detected in the gill, trunk kidney, head kidney, spleen, and heart in high concentrations, while the skin, brain, liver, and muscles contained much lower titers, indicating that EcMyD88 may play a crucial role in host innate immunologic surveillance. To identify the potential role of TLR pathways in fish anti-C. irritans immune responses, we chose three important molecules involved in anti-parasite responses, TLR2, MyD88 and IL-1b to indicate TLR pathway’s signal-in, signal transduction, and signal-out functions, respectively. The expression profile of these three genes was detected in grouper infected by C. irritans. Results showed these molecules each experience significant changes within the skin, gill (two infected mucosal sites), head kidney and spleen (two systematic immune organs) after C. irritans infection. These findings indicate the TLR signaling pathway may play an important role in host defense against C. irritans.
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Hemopexin, a high affinity heme-binding protein is widely involved in variety physiological and pathological processes. It is an important acute phase response protein, and is important in regulating the inflammatory response. In this study, the open reading frame of Nile tilapia hemopexin (OnHpx) gene was amplified. The expression pattern of OnHpx in natural and bacterial challenged tilapia tissues were analyzed through RT-qPCR. The results indicated the OnHpx was most abundant in liver, and increased significantly in liver, spleen, head kidney and peripheral blood after bacterial challenge. Furthermore, the OnHpx mRNA was also significantly up-regulated in monocytes/macrophages and hepatocytes under the stimulation of S. agalactiae or A. hydrophila. In addition, the recombinant OnHpx protein could effectively reduce the bacteria proliferation and alleviate the inflammatory reaction caused by bacteria. Moreover, the (r)OnHpx also regulated the respiratory burst of monocytes/macrophages and played an important role in the antioxidant process. To our knowledge, these results provide the first evidence on the antibacterial and anti-inflammatory response mechanism of Hpx in early vertebrates. This brings new insights about the understanding of the evolutionary origins and ancient roles of the Hpx in the innate immune defense.
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Ichthyophthirius multifiliis is a protozoan ciliate that causes white spot disease (also known as ichthyophthiriasis) in freshwater fish. Holland's spinibarbel (Spinibarbus hollandi) was less susceptible to white spot disease than grass carp (Ctenopharyngodon Idella). In this study, grass carp and Holland's spinibarbel are infected by I. multifiliis and the amount of infection is 10,000 theronts per fish. All grass carp died within 12 days after infection, and the survival rate of Holland's spinibarbel was more than 80%. In order to study the difference in sensitivity of these two fish species to I. multifiliis, transcriptome analysis was conducted using gill, skin, liver, spleen and head kidney of Holland's spinibarbel and grass carp at 48h post-infection with I. multifiliis. A total of 489,296,696 clean reads were obtained by sequencing. A total of 105 significantly up-regulated immune-related genes were obtained by Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis in grass carp. Cluster of differentiation 40 (CD40), cluster of differentiation 80 (CD 80), tumor necrosis factor-alpha (TNF-α), toll-like receptor 4 (TLR-4), interleukin 1 beta (IL-1β) and other inflammatory-related genes in grass carp were enriched in the cytokine-cytokine receptor interaction pathway and toll-like receptor pathway. In Holland's spinibarbel, a total of 46 significantly up-regulated immune-related genes were obtained by GO classification and KEGG pathway enrichment analysis. Immune-related genes, such as Immunoglobin heavy chain (IgH), cathepsin S (CTSS), complement C1q A chain (C1qA), complement component 3 (C3) and complement component (C9) were enriched in phagosome pathway, lysosome pathway and complement and coagulation concatenation pathway. C3 was significantly up-regulated in gill and head kidney. Fluorescence in situ hybridization (FISH) showed that the C3 gene was highly expressed in gill tissue of Holland's spinibarbel infected with I. multifiliis. A small amount of C3 gene was expressed in the gill arch of grass carp after infected with I. multifiliis. In conclusion, the severe inflammatory response in vivo after infecting grass carp with I. multifiliis might be the main cause of the death of grass carp. The extrahepatic expression of the gene of Holland's spinibarbel might play an important role in the immune defense against I. multifiliis.
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The defense system of teleost fish organized on innate and adaptive immunity protects them against a wide variety of pathogenic microorganisms in the aquatic environment. Phagocytosis is one of the most effective defense strategies against microbial challenge mainly performed by classical ‘professional’ phagocytes (including monocytes, macrophages and granulocytes). They contain, kill and process the internalized pathogens for antigen presentation by providing antigenic ligands to initiate activation and clonal expansion of T and B cells, which bridge the innate and adaptive immunity. The discovery of phagocytic B cells in teleost fish has broken the paradigm that primary vertebrate B cells are lack of phagocytosis of particulates, as well as led to the investigation of phagocytic activity of mammalian B-1 B cells. The active phagocytic, microbicidal capabilities and antigen presentation in teleost phagocytic B cell have demonstrated to be similar as professional phagocytes, providing a potential impact on development of new vaccination strategies to prevent and control infectious diseases. In this review, we aim to address current progress on the antimicrobial role of phagocytic B cells in teleost fish by comparing it with other professional phagocytes and mammalian B-1 B cells, and provide the application prospect of phagocytic B cells in developing vaccines as well as the prevention of fish diseases.
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Anisakidae nematode larvae is one of the most common parasites in wild anadromous Coilia nasus. This study aims to explore the mechanism of the C. nasus immune response to the parasitism of Anisakid nematode larvae. Results found that Anisakid nematode larvae parasitism caused liver injury as evidenced by histomorphology results as well as high levels of Aminotransferase and Aspertate aminotransferase. Further, Anisakid nematode larvae parasitism induced an immune response in the host, which was characterized by the elevated populations of macrophages and neutrophils in the liver and head‐kidney in the Anisakidae‐infected group than the non‐infected group. The expression of immunoglobulin IgM and IgD in the liver and head‐kidney was also increased in the Anisakidae‐infected group. The Anisakidae‐infected group showed higher activity of antioxidant enzymes catalase and superoxide dismutase, which indicates severe oxidative stress, and increased production of pro‐inflammatory cytokines, TNF‐α, IL‐6 as well as MCP‐1 in the liver compared with the non‐infected group. As a result of inflammation, livers of hosts in the Anisakidae‐infected group showed fibrosis, and elevated expression of associated proteins including α‐smooth muscle actin, fibronectin, collagen type I and type III compared with the non‐infected group. We demonstrated that Anisakid nematode larvae parasitism results in injury and fibrosis in the liver and triggers immune cell infiltration and inflammation in the liver and head‐kidney of C. nasus. Altogether, the results provide a foundation for building interaction between parasite and host, and will contribute to C. nasus population and fishery resource protection.
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A 10-week feeding trial was conducted to investigate the effects of individual and combined inclusion of phytase and protease on the growth performance, digestive ability, immune response and muscle amino acid profile of gibel carp (Carassius auratus gibelio) fed low phosphorus (LP) and/or low fish meal (LFM) diets. Seven experimental diets were designed: 1) Normal diet [PC, 15 g/kg Ca(H2PO4)2 and 80 g/kg fish meal], 2) Low P diet [10 g/kg Ca(H2PO4)2 and 80 g/kg fish meal], 3) LP + 0.4 g/kg phytase diet (LP + Ph), 4) Low fish meal diet [LFM, 15 g/kg Ca(H2PO4)2 and 50 g/kg fish meal], 5) LFM + 0.5 g/kg protease diet (LFM + Pr), 6) Low P and Low fish meal diet [LP-LFM, 10 g/kg Ca(H2PO4)2 and 50 g/kg fish meal] and 7) LP-LFM + 0.4 g/kg phytase +0.5 g/kg protease diet (LP-LFM + Ph + Pr). The results showed that the growth performance, whole body composition, nutrient digestibility, immunological indices, and muscle amino acid contents of gibel carp fed the LP, LFM and LP-LFM diets were dramatically lower than those of carp fed the normal diet (P<0.05). However, compared the LP-LFM, LFM and LP groups, dietary addition of phytase + protease, protease and phytase, respectively, (1) improved the special growth rate (SGR), weight gain rate (WGR), ADC of dry matter, crude protein and P; (2) upregulated the activities of lipase, trypsin, amylase and chymotrypsin in the liver and intestine; (3) increased liver lysozyme (LZM), superoxide dismutase (SOD), glutathione peroxidase (GPx) and total antioxidant capacity (T-AOC) levels, intestinal secreted immunoglobulin A (sIgA), complement 4 (C4) and C3 levels; (4) increased the contents of amino acids, for example, valine, leucine and methionine, in the muscle. Moreover, when both phytase and protease were added simultaneously, they had a better promoting effect than when individual added. It can be concluded that a reduction of dietary P and fish meal for gibel carp has side effects on growth performance, while phytase and protease could mitigate these effects by improving the digestive ability and immune response of gibel carp.
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Lernaea cyprinacea Linnaeus, 1758 is an ectoparasite showing widespread infections in tropical aquaculture, and the present study aimed to determine the specific immune responses against this parasite. For the experiment, whole parasite extracts were injected intraperitoneally into Cyprinus carpio Linnaeus, 1758, and samples of epidermal mucus and blood were drawn at 0, 1, 7 and 14-days post-injection (DPI). The results revealed high levels of protein, protease and lysozyme activities in the experimental fish which were injected with L. cyprinacea protein extract. In the epidermal mucus, the total protein concentration of the control fish was 460 μg/mL, and the level raised significantly to 800 μg/mL in the experimental fish. The lysozyme activity increased from 741.5 u/mL to a peak level of 1448.5 u/mL at 7DPI. The protease activity was also found elated gradually from 2.91 u/μL to 4.49 u/μL at 1 to 14 DPI. In the serum samples, the protein concentration remained steady throughout the experiment period. However, all the experimental fish displayed statistically high levels of lysozyme and protease activity, from 890 u/mL to 1220 u/mL, and 6.10 u/μL to 11.88 u/μL, respectively. In the whole blood samples, the haemoglobin content and the red blood cells (RBC) count did not show any significant change in any of the experimental groups. But, the percentage of lymphocytes showed a marginal increase from 0.47 to 0.6 in the experimental groups. Overall, the immune responses induced by L. cyprinacea protein extracts depicts a pattern of specific responses, in which the local humoral responses dominate the systemic humoral/cellular response. The results further revealed the possibility of futuristic approaches to control freshwater ectoparasites.
Thesis
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Quels mécanismes écologiques et évolutifs rendent les interactions entre espèces possibles ? J'ai abordé cette question en considérant l'interaction entre un parasite de poisson d'eau douce (Tracheliastes polycolpus) et plusieurs de ses hôtes cyprinidés. J'ai d'abord mis en avant le rôle de l'environnement à une échelle spatiale très fine (quelques centaines de mètres) sur le taux de rencontre entre ce parasite et ses hôtes. A plus large échelle spatiale (la France) j'ai illustré le rôle limitant de la résistance des populations hôtes sur la distribution de T. polycolpus. Par ailleurs j'ai montré que T. polycolpus parvient à parasiter différentes espèces hôtes en s'appuyant sur une expression plastique de ses gènes. Enfin, j'ai montré que les communautés bactériennes associées à l'hôte changent consécutivement à l'infection parasitaire dans une dynamique de co-infection avec le parasite. Par le déploiement d'approches variées et complémentaires, il apparaît que des facteurs environnementaux, liés à l'hôte, au parasite ou encore à leur cortège de bactéries contribuent à la réalisation d'une interaction étroite et durable tel que le parasitisme.
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Natural infections of rainbow trout with two species of Diphyllobothrium result in a host inflammatory response encapsulating the plerocercoid. The encapsulating cyst, observed by light and electron microscopy, comprises leucocytes, fibroblasts and collagenous connective tissue and is infiltrated with a blood vascular network. An indirect immunofluorescence technique and enzyme-linked immunosorbant assay (ELISA) have shown that specific antibodies are elicited by the fish host to these Diphyllobothrium spp. These antibodies have been semi-quantitatively measured by ELISA and correlated with worm burdens in individual fish.
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The influence of oxygenation on the immune response of sea bass (Dicentrarchus labrax) to the branchial parasite Diplectanum aequans was studied in the 'II Padule' fish-farm in Castiglione della Pescaia (Grosseto, Italy). The protein fractions of the parasite responsible for the immune response in the fish host were detected, and the sea bass stalled in hyperoxygenation conditions demonstrated a greater antigenic activity and fewer parasites than those reared in normal aeration did.
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This book is the second edition of the first of three proposed volumes on diseases and disorders in freshwater and marine fishes (fin and shellfish). Since the publication of the first edition, a tremendous volume of research has been conducted on parasites, especially those that cause morbidity and mortality in fish. Like the first edition, this book deals with parasitic infections caused by protozoans and metazoans and each chapter deals with a specific disease/disorder or a group of closely related diseases. Its primary objective is to produce a comprehensive and authoritative review from experts who are actively working in the area or have contributed to the understanding of fish diseases/disorders. Significant changes to this second edition include the addition of three new chapters and four of the original chapters have new authors. All other chapters have been thoroughly updated since the first edition was published in 1995. The book will be of significant interest to researchers and students of aquaculture, fisheries, parasitology and veterinary medicine.
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Ciliates are highly evolved protists comprising a phylum of diverse species, many of which are opportunistic or obligate parasites. Ciliates parasitic to fish consist of salt and freshwater forms with endo- or ectoparasitic modes of infection. Some of the more commonly encountered genera include Chilodonella, Brooklynella, Ophryoglenina, Ichthyophthirius, Cryptocaryon, Umnema, Tetrahymena, Epistylus, and Trichodina. Species range from obligate parasites and commensals to opportunistic, facultative forms. Some parasitic ciliates are highly pathogenic and fishes in closed environments such as aquaria and farm ponds are particularly susceptible to high mortalities. Nevertheless, fish have evolved an immune system capable of mounting an effective protective response against parasite challenge. Much of the experimental research on immunity against ciliates has been carried out with Ichthyophthirius multifiliis, on obligate parasite that invades surface epithelia of virtually all freshwater fish species. Interest in the immune response against I. multifiliis stems from the fact that convalescent fish become resistant to subsequent challenge (suggesting the possibility of immunoprophylaxis), and the need to curtail severe losses caused by this parasite in intensively farmed fishes. Furthermore, I. multifiliis has proven to be a useful experimental model because it is amenable to study under laboratory conditions. In this review cellular and humoral factors involved in both innate and acquired immunity against ciliates are covered and include natural killer cells, phagocytic cells, and antibody responses. Current ideas on the mechanisms of antibodymediated cutaneous immunity against I. multifiliis are discussed and approaches toward the development of vaccines against this and other ciliate parasites are presented.
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Ciliates are highly evolved protists comprising a phylum of diverse species, many of which are opportunistic or obligate parasites. Ciliates parasitic to fish consist of salt and freshwater forms with endo- or ectoparasitic modes of infection. Some of the more commonly encountered genera include Chilodonella, Brooklynella, Ophryoglenina, Ichthyophthirius, Cryptocaryon, Uronema, Tetrahymena, Epistylus, and Trichodina. Species range from obligate parasites and commensals to opportunistic, facultative forms. Some parasitic ciliates are highly pathogenic and fishes in closed environments such as aquaria and farm ponds are particularly susceptible to high mortalities. Nevertheless, fish have evolved an immune system capable of mounting an effective protective response against parasite challenge. Much of the experimental research on immunity against ciliates has been carried out with Ichthyophthirius multifiliis, on obligate parasite that invades surface epithelia of virtually all freshwater fish species. Interest in the immune response against I. multifiliis stems from the fact that convalescent fish become resistant to subsequent challenge (suggesting the possibility of immunoprophylaxis), and the need to curtail severe losses caused by this parasite in intensively farmed fishes. Furthermore, I. multifiliis has proven to be a useful experimental model because it is amenable to study under laboratory conditions. In this review cellular and humoral factors involved in both innate and acquired immunity against ciliates are covered and include natural killer cells, phagocytic cells, and antibody responses. Current ideas on the mechanisms of antibody-mediated cutaneous immunity against I. multifiliis are discussed and approaches toward the development of vaccines against this and other ciliate parasites are presented.
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Pronephric phagocytes from common carp Cyprinus carpio L, infected with the gut-dwelling coccidian Goussia carpelli showed enhanced phagocytic activity during the period of merogonic and gamogonic development of the parasite from Days 10 to 15 post exposure (PE) to the parasite. The respiratory burst activity was enhanced during excretion of oocysts at Days 15 to 25 PE. The addition of parasite lysates to assays resulted in an increase of phagocyte activity in cells from carp infected with gamogonic and sporogonic stages of the parasite and from carp which, at Day 35 PE, had recovered from a G. carpelli infection. The addition of immune serum sampled from fish at Days 5, 10, 15, 20, and 25 PE had no clear stimulatory effect on phagocyte activity. This suggests an activation of pronephric phagocytes on infection with the parasite. In carp with gamogonic and sporogonic parasite stages, activated macrophages show an increased cytotoxic reactivity, and activated macrophages rather than non-activated resident macrophages can be enhanced by opsonization with parasite molecules.
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Mannose-binding lectin (MBL) is an important element of the innate immune defence system. The protein binds to the sugars present on many microbial surfaces and subsequently activates the complement system through a family of specific proteases called the MASPs (MBL-associated serine proteases). Studies of MBL binding to selected Gram-negative organisms suggest that the lipopolysaccharide (LPS) structure is of primary importance. For a range of clinically relevant organisms MBL binding leads to activation and cleavage Of C4 and C3, suggesting that this is a major pathway for opsonophagocytosis. MBL deficiency, resulting from three mutations in exon 1 and polymorphisms in the promoter region of the gene, is associated with both increased susceptibility to infections and autoimmune disease. Recent evidence indicates that the protein also modulates disease severity possibly by influencing cytokine production.
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Teleosts possess mechanism(s) by which they can generate considerable structural diversity within their tetrameric antibody molecules. In salmonids, this diversity is generated through a process of random polymerisation of the constituent monomeric subunits rather than dependency upon isotypic gene diversity. Thus, one gene product can give rise to as many as six different structural forms of immunoglobulin. In contrast to mammals, evidence suggests that this polymerisation process occurs late in the secretory process and not within the endoplasmic reticulum. This assembly process is likely to be important in the generation of teleost antibody functional diversity, thereby potentially simulating isotypy.
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For many years, innate immunity has been considered as a separate entity from the adaptive immune response and has been regarded to be of secondary importance in the hierarchy of immune functions. For the past few years, however, interest in innate immunity has grown enormously, so that now it is studied intensively in many laboratories that seek to integrate these two distinct types of immune function. Our intent in this review is to point out the similarities and differences in these two types of host response to infection, and to indicate our present level of understanding of how these can be integrated into a more complete description of the immune response.
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Ultrastructural features of the actinosporean phase(A) of the myxozoan life cycle are presented and compared with corresponding structures of the myxosporean phase (M). In both A and M phases, the same essential cell structures can be found: mitochondria, sometimes with plate- or tubule-like cristae and various inclusions; Golgi in typical or modified form; rer; ribosomes, sometimes forming helices of polyribosomes; sporoplasmosomes; phagosomes; various vesicles; reserves such as lipid bodies and beta-glycogen granules; typical microtubular bundles as residues of the mitotic spindle; cell junctions in form of more or less elaborate gap- or septate junctions or desmososmes and pseudopodia-like surface projections. Centrioles are absent. There is no essential difference in the main myxozoan character, polar capsule formation and structure; the identity includes the 11- 12 nm fibers on the surface of the nascent polar filament. Very simple stem cells endowed with small amount of cytoplasm and fragments of rer (= inner cells of the pre- and extrasporogonic cycles of M and infectious cells in the A sporoplasm) have the potential to give rise to specialised cells such as sporoblast or plasmodial cells with a wide variety of cell constituents. The greatest diversity is found in M sporogonic plasmodia, with a variety of vesicles, fibrillar structures and surface modifications. In both M and A phases, unique modifications of er membranes may be found. Comparison of A and M fine structure reveals an identical structural pattern and supplies another confirmation of the unity of myxozoan life cycle. Polar capsules of myxozoa and nematocysts of cnidarians are homologous in their structure and way of origin. Septate cell junctions are typical both of chidaria and of myxozoa. These two features, in addition to a plethora of other characters support the postulated kinship of both groups. The discrepancies in the mode of mitosis, however, warrant further research of their phylogenetical relationships.
Article
Numerous investigations during the last few decades have clearly demonstrated the existence of a wide array of immune mechanisms in teleosts. An increasing amount of evidence indicates that both non-specific and specific factors in the humoral and cellular fish immune systems are well developed. However, a successful co-evolution of the host and its parasite necessitates that the latter develop evading mechanisms in order to avoid extinction. Some parasites have even understood to benefit from the well developed antiparasitic armament in fish epithelia. Thus, a range of parasites are exploiting the antiparasitic response mechanisms of the host to optimize host-finding, invasion and survival in the host. Such interactions between hosts and parasites are phylogenetically old. These dynamic interactions between hosts and invaders have been observed in various branches of fish parasitology. Experiments with protists such as Ichthyophthirius multifiliis and monogeneans such as Gyrodactylus derjavini indicate that parasites are activated by factors in host mucus (first line of defence) and actively search for epithelia rich in mucous cells. Some monogeneans, cestodes, digeneans, acanthocephalans and crustaceans are able to resist pronounced cellular host reactions which even will improve the attachment of the parasites to the host tissue. Despite these evading mechanisms in the parasites it is possible to use immunoprophylactic measures to control infections. Some parasites are indeed actively rejected by their potential hosts provided these are effectively immunized at certain early points before infection.
Article
This book is the second edition of the first of three proposed volumes on diseases and disorders in freshwater and marine fishes (fin and shellfish). Since the publication of the first edition, a tremendous volume of research has been conducted on parasites, especially those that cause morbidity and mortality in fish. Like the first edition, this book deals with parasitic infections caused by protozoans and metazoans and each chapter deals with a specific disease/disorder or a group of closely related diseases. Its primary objective is to produce a comprehensive and authoritative review from experts who are actively working in the area or have contributed to the understanding of fish diseases/disorders. Significant changes to this second edition include the addition of three new chapters and four of the original chapters have new authors. All other chapters have been thoroughly updated since the first edition was published in 1995. The book will be of significant interest to researchers and students of aquaculture, fisheries, parasitology and veterinary medicine.
Article
This book is the second edition of the first of three proposed volumes on diseases and disorders in freshwater and marine fishes (fin and shellfish). Since the publication of the first edition, a tremendous volume of research has been conducted on parasites, especially those that cause morbidity and mortality in fish. Like the first edition, this book deals with parasitic infections caused by protozoans and metazoans and each chapter deals with a specific disease/disorder or a group of closely related diseases. Its primary objective is to produce a comprehensive and authoritative review from experts who are actively working in the area or have contributed to the understanding of fish diseases/disorders. Significant changes to this second edition include the addition of three new chapters and four of the original chapters have new authors. All other chapters have been thoroughly updated since the first edition was published in 1995. The book will be of significant interest to researchers and students of aquaculture, fisheries, parasitology and veterinary medicine.
Article
This book is the second edition of the first of three proposed volumes on diseases and disorders in freshwater and marine fishes (fin and shellfish). Since the publication of the first edition, a tremendous volume of research has been conducted on parasites, especially those that cause morbidity and mortality in fish. Like the first edition, this book deals with parasitic infections caused by protozoans and metazoans and each chapter deals with a specific disease/disorder or a group of closely related diseases. Its primary objective is to produce a comprehensive and authoritative review from experts who are actively working in the area or have contributed to the understanding of fish diseases/disorders. Significant changes to this second edition include the addition of three new chapters and four of the original chapters have new authors. All other chapters have been thoroughly updated since the first edition was published in 1995. The book will be of significant interest to researchers and students of aquaculture, fisheries, parasitology and veterinary medicine.
Article
Detection of and response to microbial infections by the immune system depends largely on a family of pattern-recognition receptors called Toll-like receptors (TLRs). These receptors recognize conserved molecular products derived from various classes of pathogens, including Gram-positive and -negative bacteria, DNA and RNA viruses, fungi and protozoa. Recognition of ligands by TLRs leads to a series of signaling events resulting in induction of acute responses necessary to kill the pathogen. TLRs are also responsible for the induction of dendritic cell maturation, which is responsible and necessary for initiation of adaptive immune responses. Although TLRs control induction of adaptive immunity, it is not clear at this point how responses are appropriately tailored by individual TLRs to the advantage of the host.
Chapter
This book is the second edition of the first of three proposed volumes on diseases and disorders in freshwater and marine fishes (fin and shellfish). Since the publication of the first edition, a tremendous volume of research has been conducted on parasites, especially those that cause morbidity and mortality in fish. Like the first edition, this book deals with parasitic infections caused by protozoans and metazoans and each chapter deals with a specific disease/disorder or a group of closely related diseases. Its primary objective is to produce a comprehensive and authoritative review from experts who are actively working in the area or have contributed to the understanding of fish diseases/disorders. Significant changes to this second edition include the addition of three new chapters and four of the original chapters have new authors. All other chapters have been thoroughly updated since the first edition was published in 1995. The book will be of significant interest to researchers and students of aquaculture, fisheries, parasitology and veterinary medicine.
Article
The potential immunosuppressive effect of elevated water temperature on resistance to Ceratomyxa shasta infection and disease (ceratomyxosis) was assessed in juvenile Klamath River chinook salmon, Oncorhynchus tshawytscha, and steelhead, Oncorhynchus mykiss. Mortality and clinical signs of ceratomyxosis were similar between juvenile salmon infected with C. shasta and then reared at water temperatures of 16° and 20°C. A 3-day (d) exposure in the upper Klamath River, during June 2002, resulted in a 100% prevalence of infection and mortality of ≥ 83% within 17-d postexposure among salmon at both water temperatures. Measures of nonspecific defense mechanisms (plasma complement and lysozyme activities, and anterior kidney cell phagocytosis) in uninfected, controlfish held at 16° and 20°C were similar to each other and within normal ranges. In contrast, plasma lysozyme activity of C. shasta infected salmon was approximately 2X higher than control fish. Phagocytosis and plasma complement activity of infected and control salmon were similar until ceratomyxosis was quite advanced. Non-specific immune parameters were not affected in salmon held at 20°C. It appears the magnitude of parasite challenge has a stronger influence on disease severity than rearing temperature. Regardless of rearing temperature, salmon challenged with an intra-peritoneal injection of C. shasta trophozoites demonstrated a strong inflammatory defense against the parasites. Juvenile steelhead exposed for 3-d to Klamath River water and then reared at 14°, 18°, and 20°C did not develop ceratomyxosis. Ceratomyxa shasta was not detected in the exposed steelhead by either Polymerase Chain Reaction (PCR) assay or histology. Salmon exposed along with the steelhead experienced typical ceratomyxosis. Steelhead rearing or migrating in the Klamath River would appear to be at low risk for ceratomyxosis. When exposed to high C. shasta actinospore levels, the ecological outcome (death) for salmon will tend to be equal under moderate spring temperatures as well as higher summer temperatures.
Article
The immobilization antigens (i-antigens) of Ichthyophthirius multifiliis are potential vaccine candidates for the prevention of 'white spot' disease in freshwater fish. These antigens vary with respect to antigenicity and molecular mass, and at least five i-antigen serotypes have been identified among parasite isolates thus far. In previous studies. the gene and corresponding cDNA encoding a similar to 48 kDa i-antigen from parasite isolate G1 (serotype A). had been cloned and sequenced. We now report on the isolation of two new genes, designated IAG52A[G5] and 1,4G52B[G5]. encoding similar to 52/55 kDa i-antigens from a parasite isolate representing a different serotype. namely. D. Based on their deduced sequences, the similar to 52/55 kDa gene products have the same structural features as the 48 kDa protein including hydrophobic N- and C-termini. periodic cysteine residues with the potential for metal binding, and tandemly repetitive amino acid sequence domains that span their length. Nevertheless. the products of these genes vary in their tandem repeat copy number, and share only similar to 50% homology overall. When expressed in heterologous systems. the products Of the newly described genes react strongly with monospecific polyclonal antisera against the i-antigens of serotype D and are clearly i-antigens. It would nevertheless appear that mRNA transcripts from the two genes are present at widely different levels within parasites themselves. Analysis at the protein level using 2-D SDS-PAGE would further suggest that multiple i-antigens are expressed within the same serotype at any given time.
Article
Two-year-old tiger puffer Takifugu rubripes, persistently infected with the monogenean Heterobothrium okamotoi for longer than one year, were cohabitated in an aquarium with one-year-old tigerpuffer with no previous record of infection (naïve fish) for 70 days. The infection level in the naïve fish rose sharply, and the intensity of infection reached its highest on day 30 (estimated 16,700 parasites on the gills per fish). In the persistently infected fish, on the other hand, no change was recorded in the infection level, which was much lower than that of the naïve fish. Based on the compositions of parasite developmental stages in the two fish groups, we hypothesize that the protection mechanism found among the persistently infected fish functioned in at least three occasions: firstly when the oncomiracidium settled on the gills, secondly when the parasite developed from a worm without clamps to one with a pair of clamps, and thirdly when it migrated and grew on the branchial cavity wall. The persistently infected fish produced anti-Heterobothrium antibodies, while no antibody was detected in the naïve fish. These results suggest that a persistent infection induces protection against H. okamotoi, but the factors responsible for effective prevention against reinfection remain to be clarified.
Article
The humoral immune response of ayu (Plecoglossus altivelis) to the microsporidian parasite Glugea plecoglossi was investigated. The antibody levels of sera from ayu, to which G. plecoglossi spores were administered orally, were measured by indirct ELISA. While the cysts appeared from 27 D.P.I. (days post-infection), the antibodies against the intact spores were first detected at 10 D.P.I. and no more significant increases in the antibody levels were observed. The uptake of spores through the gut epithelium was histologically observed. Additionally, sera from ayu in a cultured stock which showed 50% prevalence of infection were obtained and the antibody levels were measured by the ELISA. The antibody level was variable but no important difference was observed between fish with or without cysts. The intensity of infection (number of cysts) was not related to the antibody level both in the artificially and naturally-infected fish. These results suggest that the antibody production against the intact spores of G. plecoglossi plays no protective role against G. plecoglossi infection.
Article
It has been known for over a decade that IL-1 bioactivity exists in fish. Recently IL-1 has been cloned in several teleost species using two different approaches; homology cloning or a suppression subtractive PCR technique. One of the most important differences of the fish sequences compared with mammalian IL-1 is the lack of a clear ICE cut site, and it remains to be determined whether the fish molecule is processed to a mature peptide. The IL-1 gene organisation has also been determined for rainbow trout, and Southern blot analysis suggests at least one related gene is present in this species. Expression of the IL-1 transcript can be induced in vitro by stimulation of head kidney leucocytes with LPS or PHA, or in vivo by challenge with Gram-negative bacteria. A number of incompletely spliced transcripts have also been detected in tissues from challenged fish.
Article
This chapter examines the different aspects of the specific immune system in fish. Specific immune responses that are independent of antibody are collectively termed as “cell-mediated immunity.” A number of thymectomy experiments have been performed to determine whether the fish thymus is a source of helper T cells and/or suppressor cells. The outcome of the removal of the thymus in fish appears to depend on the completeness of the operation, the stage of the development of the fish, the interval between thymectomy and immunization, and many other factors, including the type and dose of antigen used. The results are compatible with the premise that the thymus is a source of T cells. The requirement for accessory cells for the activation of T lymphocytes by mitogens has been confirmed for channel catfish peripheral blood lymphocytes. Interleukin-2 (IL-2) was formerly known as “T-cell growth factor” in recognition of its ability to induce the proliferation of T-cells. In mammals, IL-2 is produced primarily by helper (CD4+ve T) cells, although other subsets of T cells may also be involved. The production of factors with IL-2-like activity in a mixed leukocyte reaction of fish has been demonstrated for carp with peripheral blood and pronephric leukocytes.
Article
This chapter describes the morphology and mechanism of cellular defenses in fish. A variety of leukocyte types is involved in nonspecific cellular defenses of fish and includes monocytes/ macrophages, granulocytes, and nonspecific cytotoxic cells (NCCs). Macrophages and granulocytes are mobile phagocytic cells found in the blood and secondary lymphoid tissues and are particularly important in inflammation, which is the cellular response to microbial invasion and/or tissue injury leading to the local accumulation of leukocytes and fluid. Isolated granulocytes are highly mobile and phagocytic and produce reactive oxygen species, but their bactericidal activity is often relatively poor compared with macrophages. A variety of approaches have been used to enrich for NCCs, including dissociation from tumor target cells, density gradient centrifugation, and flow cytometry. The development of inflammatory reactions is controlled by a number of mediators, including cytokines, eicosanoids, complement factors, and other vasoactive compounds released from phagocytes and thrombocytes.
Article
Ultrastructural changes in cells of carp Cyprinus carpio (L.) spleen and pronephros were studied after experimentally infecting each fish with 500 Sanguinicola inermis cercariae. Cells were identified morphologically and counted within transmission electron microscope preparations of tissues from carp killed 5 and 9 wk post-infection. Results were compared with cell counts in uninfected controls. In the spleen, parasitism induced significant reductions of erythrocytes (p < 0.001), neutrophils (p < 0.01) and eosinophils (p < 0.001) and significant increases of thrombocytes (p < 0.001) and macrophages (p < 0.001). In the pronephros, following infection, there were significant reductions of erythrocytes (p < 0.05), lymphocytes (p < 0.05), thrombocytes (p < 0.05) and eosinophils (p < 0.001) and significant increases of macrophages (p < 0.001) and neutrophils (p <0.001). These changes are believed to be associated with the presence of adult S. inermis in the host vascular system and/or eggs which become entrapped in host tissues.
Article
The capacity of certain salmonids to resist infection and disease caused by the myxosporean Ceratomyxa shasta is well known. Observations of differential mortality among strains suggest that intraspecies differences in susceptibility developed as a result of selective pressure in waters where the parasite is enzootic. Research efforts have identified resistant strains for use in stocking programs and examined the heritability of the trait. This paper reviews the research on resistance of salmonids to C. shasta, the conclusions drawn from these studies, and how this information has been applied.
Article
After an epizootic of amyloodiniosis (caused by the protozoan Amyloodinium ocellatum) in a commercial aquaculture facility for hybrid striped bass (female striped bass Morone saxatilis × male white bass M. chrysops), sera from these fish, as well as from others that had been experimentally immunized with the parasite, were evaluated by an enzyme-linked immunosorbent assay for antibody specific for the parasite. Titers were similar between the fish infested in culture and the experimentally immunized fish, and were significantly higher in both the cultured and artificially exposed fish than in unexposed fish. These results suggest that an infestation of A. ocellatum can stimulate the production of humoral antibodies to the parasite, providing further evidence that natural infestations of the parasite may confer protective resistance in fish that survive the initial parasitic infestation.
Article
The nature of rodlet cells (RCs) and their functions is subject to a number of different interpretations. This review provides a detailed analysis of the parasitic and endogenous origin of these cells. Two new functional aspects of RCs are considered in detail. The possible function of RCs as immune cells was derived from studies that reported an increase in the number of RCs in fish infected with protozoan and metazoan parasites, particularly at the site of the pathogen infection and/or attachment. Accordingly, RCs represent inflammatory cells, with a similar role to eosinophile granule cells, epithelioid cells and mesothelial cells. Rodlet cells may potentially act as biomarkers. Experimental studies that examined the response of RCs in fish exposed to chemical substances such as metals and herbicides reported an increase in the number of RCs in the tissues of the fish. Fish exposed to these substances expressed myelinic figures in the cytoplasm of the RCs and various degrees of rodlet degeneration and high vacuolization of RC cytoplasm were often noticed. Further lines of research are suggested that might elucidate the true function of these enigmatic cells.
Article
A histological, histochemical and ultrastructural examination of the skin of wild and cultured plaice was carried out, using fish from each year class from 0+ to 4+. The skin was shown to be similar in general structure to that of other teleosts but a previously undescribed cell, designated the Eosinophilic Granular Cell, a dendritic secretory cell found throughout the basal layers of the epidermis, is described. It was fixed only by formalin or dichromate, and contained numerous acidophilic granules. Melanin-bearing macrophages were observed migrating through the epithelium, but no DOPA or tyrosinase positive cells were observed by the methods used. Mast cells were very common in the dermis but were only demonstrable by special techniques. The melanophore and guano-phore systems are described and although no melanophores or melanocytes were found in the unpigmented areas of partially pigmented hatchery-reared fish, the integrity of the guanophore system was complete in such fish.
Article
Procercoids of Diphyllobothrium dendriticum were incubated for 5 or 24 h with rainbow trout head kidney leucocyte suspension in vitro, in the absence or presence of complete and/or incomplete (heat inactivated) normal or specific immune serum. Neutrophils and macrophages were the predominant leucocytes that were found to adhere to the procercoid tegument, although a third unidentified leucocyte type was also seen. Leucocyte adherence was considerably increased by the presence of immune serum, indicating a possible interaction between the non-specific and specific immune response in the host inflammatory reaction to this parasite. Indeed, it was only in the presence of immune serum that damage to the procercoid tegument occurred. Production of both hydrogen peroxide and superoxide anion from macrophages was induced by antigen extracts from plerocercoids of D. dendriticum, prepared either by freezing and thawing specimens or by culturing live plerocercoids in vitro to obtain a conditioned medium. The possibility that reactive oxygen species contribute to the damage observed in the adherence assays is discussed.