Article

Chicken Parvovirus–Induced Runting-Stunting Syndrome in Young Broilers

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Abstract

Previously we identified a novel parvovirus from enteric contents of chickens that were affected by enteric diseases. Comparative sequence analysis showed that the chicken parvovirus (ChPV) represented a new member in the Parvoviridae family. Here, we describe some of the pathogenic characteristics of ChPV in young broilers. Following experimental infection, 2-day-old broiler chickens showed characteristic signs of enteric disease. Runting-stunting syndrome (RSS) was observed in four of five experimental groups with significant growth retardation between 7 and 28 days postinoculation (DPI). Viral growth in small intestine and shedding was detected at early times postinoculation, which was followed by viremia and generalization of infection. ChPV could be detected in most of the major tissues for 3 to 4 wk postinoculation. Immunohistochemistry staining revealed parvovirus-positive cells in the duodenum of inoculated birds at 7 and 14 DPI. Our data indicate that ChPV alone induces RSS in broilers and is important determinant in the complex etiology of enteric diseases of poultry.

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... Clinical signs: Clinical signs recorded in enteritis affected birds include reduced feed intake, depression, diarrhea, dehydration, vent pasting, ruffled feathers, partially digested food material in faeces and stunted and poor growth. Similar symptoms were also reported by Zsak et al., (2013) [23] and Nunez et al., (2020) [13] during experimental ChPV infection in chickens. Altered growth performance may be attributed due to impairment in enzymatic digestion and absorption of nutrients from the gastrointestinal tract as the virus targets the pancreas and intestinal tract (Rebel et al., 2006) [16] . ...
... Clinical signs: Clinical signs recorded in enteritis affected birds include reduced feed intake, depression, diarrhea, dehydration, vent pasting, ruffled feathers, partially digested food material in faeces and stunted and poor growth. Similar symptoms were also reported by Zsak et al., (2013) [23] and Nunez et al., (2020) [13] during experimental ChPV infection in chickens. Altered growth performance may be attributed due to impairment in enzymatic digestion and absorption of nutrients from the gastrointestinal tract as the virus targets the pancreas and intestinal tract (Rebel et al., 2006) [16] . ...
... In some cases, undigested feed in thin walled swollen intestines and catarrhal enteritis was evident. Similar lesions were reported in enteritis due to ChPV (Zsak et al., 2013;Pradeep et al., 2020) [15,23] . Microscopically, the prominent changes were observed in duodenum, jejunum and caeca. ...
Article
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Enteritis is one of important disease of chickens characterized by diarrhoea, poor weight gain and in some flocks, high mortality. Chicken Parvovirus (ChPV) is one of the important viral agents involved in enteric disorders. The present study was aimed to detect the ChPV associated with enteritis in desi and kadaknath chickens of Chhattisgarh. Total of 151 desi and kadanath birds (1-18 weeks old) died due to enteritis with symptoms of diarrhea, vent pasting, ruffled feathers and poor growth were subjected to necropsy. Intestinal tissue samples collected from 151 birds were subjected to PCR assay for detection of ChPV by amplifying 561 bp sequence of NS gene. ChPV was detected in 31.78% (48/151) of intestinal samples collected chickens of Durg, Rajnandgaon, Balod and Raipur district of Chhattisgarh which suffered from enteritis. Lesions consisted of catarrhal enteritis, dilated, inflamed or pale intestinal wall with watery and gas filled contents, atrophy of immune organs and pancreas. Sequences of NS gene of ChPV showed 98.37%-99.19% nucleotide similarities with other previously published sequences. Phylogenetic analysis revealed that detected Indian isolate is grouped with Poland 1 and USA 2 isolates. The results indicated the presence of ChPV in Indian chicken flocks and its close association with enteritis.
... In the field, outbreaks that affected chickens showed many pathological alterations in the intestine upon postmortem examination, showing mainly distended intestines filled with aqueous feces and foamy and undigested feed. Moreover, the challenge with outbreaks in the field is the association of ChPV with other enteric viruses or bacteria, which could decrease the quality of the gut integrity [4,16,22,23,31]. Experimental infections with isolated ChPV (ABU-P1) have demonstrated that the virus causes enteric diseases, resulting mainly in chickens with diarrhea, cloacal pasting, impaired growth, runting and stunting [32]. ...
... As reported in the present investigation, the principal clinical signs present in the infected animals were also diarrhea, cloacal pasting, somnolence, apathy, ruffled feathers, impaired growth, runting and stunting. However, the ChPV strain ABU-P1 does not cause any macroscopic lesions in enteric tissues [22,32]. ...
... The enteric diseases caused by bacteria or viruses (RSS) have the particularity of presenting alterations at the ciliated columnar epithelium, Lieberkühn crypts, and in intestinal villi, which show atrophy and fusion or expansion of the lamina propria as a result of inflammatory infiltrates [7,26,33]. Nevertheless, experimental infections with ChPV (ABU-P1) have reproduced RSS, but microscopic alterations were not found in the intestines or in any other organ [22]. In the present investigation, we demonstrated the presence of crypt alterations, which were characterized principally by dilated crypts lined by a squamous epithelium that contained cellular debris and degenerate inflammatory cells, a cyst shape and crypt cell necrosis, all of which are present in the segment of the rolled duodenal loop and in other segments of the intestine; thus, these findings microscopically characterize the ChPV strain isolated in Brazil. ...
Article
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Chicken parvovirus (ChPV) is an agent frequently associated with runting stunting syndrome (RSS). This syndrome has been reported in association with ChPV in many countries, including Brazil; however, studies characterizing the virus on a molecular level are scarce, and ChPV pathogenicity in day-old chicks remains unclear. The aim of the present work was to establish the molecular characteristics of ChPV, determine the pathogenicity of ChPV in SPF chicks and detect and quantify ChPV by qPCR in several tissues and chicks of different ages. The experimental challenge was performed at one day of age, and daily and weekly observations were performed and five birds from each experimental group (mock and infected birds) were euthanized to perform the different analysis. ChPV genome copies were detected and quantified by qPCR in gut, spleen, thymus, kidney, pancreas, proventriculus and bursa. Clinically, the infected group presented with diarrhea 24 h post-infection, which persisted until 42 days of age. The small intestine was distended, and its contents were aqueous and foamy. Enteritis and dilated crypts with cyst shapes were observed in intestinal segments. Acute pancreatitis associated with lymphocytic nodules, infiltrating lymphocytes and plasma cells between the pancreatic acinus was observed. Koch’s postulate was demonstrated and the genetic characterization of the VP1 gene showed that the Brazilian ChPV isolate belongs to the ChPV II group.
... Clinical signs: Clinical signs recorded in enteritis affected birds include reduced feed intake, depression, diarrhea, dehydration, vent pasting, ruffled feathers, partially digested food material in faeces and stunted and poor growth. Similar symptoms were also reported by Zsak et al., (2013) [23] and Nunez et al., (2020) [13] during experimental ChPV infection in chickens. Altered growth performance may be attributed due to impairment in enzymatic digestion and absorption of nutrients from the gastrointestinal tract as the virus targets the pancreas and intestinal tract (Rebel et al., 2006) [16] . ...
... Clinical signs: Clinical signs recorded in enteritis affected birds include reduced feed intake, depression, diarrhea, dehydration, vent pasting, ruffled feathers, partially digested food material in faeces and stunted and poor growth. Similar symptoms were also reported by Zsak et al., (2013) [23] and Nunez et al., (2020) [13] during experimental ChPV infection in chickens. Altered growth performance may be attributed due to impairment in enzymatic digestion and absorption of nutrients from the gastrointestinal tract as the virus targets the pancreas and intestinal tract (Rebel et al., 2006) [16] . ...
... In some cases, undigested feed in thin walled swollen intestines and catarrhal enteritis was evident. Similar lesions were reported in enteritis due to ChPV (Zsak et al., 2013;Pradeep et al., 2020) [15,23] . Microscopically, the prominent changes were observed in duodenum, jejunum and caeca. ...
Article
Full-text available
Enteritis is one of important disease of chickens characterized by diarrhoea, poor weight gain and in some flocks, high mortality. Chicken Parvovirus (ChPV) is one of the important viral agents involved in enteric disorders. The present study was aimed to detect the ChPV associated with enteritis in desi and kadaknath chickens of Chhattisgarh. Total of 151 desi and kadanath birds (1-18 weeks old) died due to enteritis with symptoms of diarrhea, vent pasting, ruffled feathers and poor growth were subjected to necropsy. Intestinal tissue samples collected from 151 birds were subjected to PCR assay for detection of ChPV by amplifying 561 bp sequence of NS gene. ChPV was detected in 31.78% (48/151) of intestinal samples collected chickens of Durg, Rajnandgaon, Balod and Raipur district of Chhattisgarh which suffered from enteritis. Lesions consisted of catarrhal enteritis, dilated, inflamed or pale intestinal wall with watery and gas filled contents, atrophy of immune organs and pancreas. Sequences of NS gene of ChPV showed 98.37%-99.19% nucleotide similarities with other previously published sequences. Phylogenetic analysis revealed that detected Indian isolate is grouped with Poland 1 and USA 2 isolates. The results indicated the presence of ChPV in Indian chicken flocks and its close association with enteritis.
... Runting-stunting syndrome (RSS) is a pathogen that afflicts young, one-week-old chicks, causing poor feed conversion, stunting, dwarfism, culling and mortality [1][2][3]. Generally, the chicks present with depression, apathy, ruffled feathers, cloacal pasting, and the most characteristic signs, diarrhea and unsteadiness [3,4]. The etiological agents related to RSS remain unknown; however, many viruses have been detected and implicated as causative agents of the disease, including astroviruses, coronaviruses, rotaviruses, reovirus, parvovirus, and others [5][6][7][8][9][10]. ...
... Runting-stunting syndrome (RSS) is a pathogen that afflicts young, one-week-old chicks, causing poor feed conversion, stunting, dwarfism, culling and mortality [1][2][3]. Generally, the chicks present with depression, apathy, ruffled feathers, cloacal pasting, and the most characteristic signs, diarrhea and unsteadiness [3,4]. The etiological agents related to RSS remain unknown; however, many viruses have been detected and implicated as causative agents of the disease, including astroviruses, coronaviruses, rotaviruses, reovirus, parvovirus, and others [5][6][7][8][9][10]. ...
... Many experimental infections have been carried out using isolated enteric viruses, such as astrovirus, avian nephritis virus (ANV), rotavirus, and Chicken Parvovirus (ChVP), to elucidate the pathogenesis of RSS [6,12,13]. These studies have determined the ChPV might be an etiological agent associated with RSS and could be considered a principal causal agent of this enteric disease [3,14]. Additionally, in Muscovy ducks, ChPV causes Derzsy's disease [15]. ...
Article
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Many viruses have been associated with runting and stunting syndrome (RSS). These viral infections mainly affect young chickens, causing apathy, depression, ruffled feathers, cloacal pasting, and diarrhea. Chicken Parvovirus (ChPV) is such an infection and has been detected in chickens showing signs of enteric diseases worldwide. Therefore, the present study aims to develop a sensitive real-time fast-qPCR assay based on SYBR® Green for detection and quantification of ChPV. A 561-bp non-structural (NS) gene was amplified and cloned, and a pair of primers was designed based on conserved nucleotide sequences on the NS gene of ChPV, the intercalating DNA reagent SYBR® Green was employed, and the Fast mode of a thermocycler was used. The assay detects 109 to 101 copies of the genome (CG). The limit of detection (LoD) was estimated to five CG, and the limit of quantification (LoQ) was estimated at ten CG. The standard curve efficiency was 101.94%, and the melting curve showed a unique clean peak and a melting temperature of 79.3 °C. The assay was specific to amplify the ChPV NS gene, and no amplification was shown from other viral genomes or in the negative controls. A total of 141 samples were tested using the assay, of which 139 samples were found positive. The highest CG value of ChPV was 5.7 × 106 CG/uL of DNA without apparent clinical signs of enteric disturbance, and 4.6 × 106 CG/uL DNA were detected in chickens with RSS.
... ChPV is related to enteric diseases that cause diarrhoea, growth retardation and lower than average weight gain, specially in 2-to 7-year-old chicks, and it is considered to be one of the aetiological agents for RSS (Zsak et al., 2013). This syndrome is also called malabsorption syndrome (MAS), helicopter disease, infectious stunting syndrome and brittle bone disease (Finkler et al., 2016).Viral replication and pathogenic effects mainly occur in cells with high proliferative rates (Hueffer & Parrish, 2003). ...
... ChPV has a worldwide distribution, and it has been associated with enteric diseases in many other countries (Kisary et al., 1984;Decaesstecker et al., 1986;Goodwin et al., 1990;Zsak et al., 2008Zsak et al., ,2009Bidin et al., 2011;Domanska-Blicharz et al., 2012;Tarasiuk et al., 2012;Nuñez et al., 2016). Experimentally, ChPV produces intestinal alterations such as diarrhoea, reduced weight gain and growth retardation (Zsak et al., 2013). In the present study, we searched for the presence of ChPV in different imprints of organs fixed in FTA cards collected from birds with enteric problems, such as diarrhoea and stunting. ...
... In the present study, we searched for the presence of ChPV in different imprints of organs fixed in FTA cards collected from birds with enteric problems, such as diarrhoea and stunting. The results showed the presence of ChPV in 50.6% of the collected samples, demonstrating that the virus is not only related to enteric organs but also to organs of other systems, such as respiratory (trachea, lungs, and air sacs), immune (thymus, bursa, bone marrow and spleen), and urinary (kidney) organ, as previously demonstrated in the experimental studies of Zsak et al. (2013) and Domanska-Blicharz et al. (2012). ...
Article
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Enteric diseases affect poultry and cause important economic losses in many countries worldwide. Avian parvovirus has been linked to enteric conditions, such as malabsorption and runting-stunting syndrome (RSS), characterized by diarrhoea, and reduced weight gain and growth retardation. In 2013 and 2016, 79 samples were collected from different organs of chickens in Ecuador that exhibited signs of diarrhea and stunting syndrome, and analysed for the presence of chicken parvovirus (ChPV). The detection method of ChPV applied was Polymerase Chain Reaction (PCR), using primers designed from the conserved region of the viral genome that encodes the non-structural protein NS1. Out of the 79 samples, 50.6% (40/79) were positive for ChPV, and their nucleotide and amino acid sequences were analysed to determine their phylogenetic relationship with the sequences reported in the United States, Canada, China, South Korea, Croatia, Poland, Hungary, and Brazil. Strong similarity of nucleotide and amino acid sequences among all analyzed sequences and between the analysed and reference sequences was demonstrated, and the phylogenetic analysis clustered all the sequences within the same group, demonstrating a strong relation between the studied strains and the reference chicken parvovirus strains.
... These enteric viruses of which several RNA and DNA viruses have been implicated, pre-dominantly affect young birds although they may occur in all age groups of poultry. Further, coinfections of multiple viruses such as chicken astrovirus (CAstV), avian nephritis virus (ANV), chicken parvovirus (ChPV), avian rotavirus (AvRV), avian reovirus (ARV), and fowl adenovirus (FAdV) have been reported in birds affected with RSS or with poor performance (6)(7)(8)(9). In addition, chickens without symptoms of enteric disease have tested positive for these viruses (9,10), indicating that they could serve as asymptomatic carriers or reservoirs shedding the virus via the enteric route and thus representing a potential source of infection to clean birds. ...
... This is consistent with the report of Nunez et al. (1) who also detected CAstV and ANV in intestinal samples of broilers with RSS. Although several studies worldwide (1,7,8,30) have detected these enteric viruses in malabsorption diseases such as RSS in chickens, our findings support the proposition that CAstV is the major aetiological agent of RSS in poultry (31,32) since not only were all the 40 sample pools positive for CAstV alone, but the strains of the virus detected in 32 of the samples tested were virtually identical. This strongly suggests that this particular strain is the cause of the runtingstunting and hatchery condemnations seen in the sampled birds. ...
... Chicken astrovirus, ANV, ChPV, FAdV, and ARV are important pathogens responsible for poor growth performance and silent losses in the poultry industry. These viruses have been detected in chicken flocks with growth retardation, bad feathering and enteritis worldwide (8,30,38). Therefore, their detection in day-old broiler chicks in this study corroborates earlier reports that broiler birds are most susceptible to viral infections during the early post-hatching period (30,38), and further confirms that these viruses are vertically transmitted. However, the detection of CAstV, ANV, and ChPV in older birds is an indication of persistent infection and horizontal transmission. ...
Article
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Enteric viruses are known to have significant economic impact on poultry, especially broiler chicken flocks, because of production losses attributable to poor feed conversion and weight gain. To sustain the Nigerian poultry industry that contributes significantly to the livestock sector of the economy, there is a need to investigate commercial broiler flocks in the country for the presence of enteric viruses causing runting and stunting, growth retardation, and hatchery diseases. Gut contents were collected from 158 day-old and six 14-week old runted/stunted broiler chickens in commercial farms (ten) and hatcheries (six) located in Southwest Nigeria. The samples were examined for the presence of chicken astrovirus (CAstV), avian nephritis virus (ANV), avian rotavirus (AvRV), chicken parvovirus (ChPV), and turkey astroviruses (TAstV-1 and−2) by polymerase chain reaction (PCR) and reverse transcriptase-PCR (RT-PCR) whereas avian reovirus (ARV) and fowl adenovirus (FAdV) by virus isolation (VI), RT-PCR, and PCR. While CAstV was detected in all the birds (100%), sporadic detection of ANV (5%), and ChPV (5%) was observed in day-old and/or older birds. Four isolates were obtained by VI with one isolate being ARV positive and other three FAdV positive by RT-PCR and PCR, respectively. These findings strongly suggest CAstV as a major cause of runting and stunting as well as hatchery condemnations in commercial broilers in Southwest Nigeria, although co-infections with ANV, FAdV, ARV, and ChPV cannot be ruled out. In addition, the possible vertical and horizontal transmissions of these viruses are discussed.
... In birds naturally-or experimentally-infected with aveparvovirus, transmission electron microscopy (TEM) studies revealed the presence of parvoviruslike particles in the intestinal content (Kisary, 1985;Murgia et al., 2012). The parvovirus-specific nuclear staining was observed in epithelial cells and inflammatory cells from small intestine in both chicken and turkey samples (Kisary, 1985;Zsak et al., 2013). Moreover, among all tissues, the intestines of affected birds contained the highest parvoviral loads (Finkler et al., 2016). ...
... Moreover, among all tissues, the intestines of affected birds contained the highest parvoviral loads (Finkler et al., 2016). Altogether, these findings suggested that enterocytes of the small intestine and the local inflammatory cells are the primary target cells for parvovirus Zsak et al., 2013;Nuñez et al., 2016). ...
... Since there is no established cell culture or embryonated eggs system, an indirect immunofluorescence assay was developed for detection of viral antigen to monitor virus infections in broiler flocks (Kisary, 1985). The ChPV and TuPV antigens were detected by indirect immunohistochemistry (IHC) in the epithelial cells of the small intestine from naturally-or experimentally-infected birds Zsak et al., 2013). An ELISA has been developed using recombinant parvovirus VP1 or VP2 protein to detect parvovirus-specific antibodies in serum of broiler chickens and maternal antibodies in young birds Spatz et al., 2013). ...
Article
Poultry parvoviruses identified during the early 1980s are found worldwide in intestines from young birds with enteric disease syndromes as well as healthy birds. The chicken parvovirus (ChPV) and turkey parvovirus (TuPV) belong to the Aveparvovirus genus within the subfamily Parvovirinae. Poultry parvoviruses are small, non-enveloped, single-stranded DNA viruses consisting of three open reading frames, the first two encoding the non-structural protein (NS) and nuclear phosphoprotein (NP) and the third encoding the viral capsid proteins 1 (VP1 and VP2). In contrast to other parvoviruses, the VP1-unique region does not contain the phospholipase A2 sequence motif. Recent experimental studies suggested the parvoviruses to be the candidate pathogens in cases of enteric disease syndrome. Current diagnostic methods for poultry parvovirus detection include PCR, real-time PCR, enzyme linked immunosorbent assay using recombinant VP2 or VP1 capsid proteins. Moreover, sequence-independent amplification techniques combined with next-generation sequencing platforms have allowed rapid and simultaneous detection of the parvovirus from affected and healthy birds. There is no commercial vaccine; hence, the development of an effective vaccine to control the spread of infection should be of primary importance. This review presents the current knowledge on poultry parvoviruses with emphasis on taxonomy, phylogenetic relationship, genomic analysis, epidemiology, pathogenesis and diagnostic methods.
... These findings seem to suggest that polymicrobial interactions might be involved in triggering this condition (Domanska-Blicharz et al., 2012;Palade et al., 2011). One of such agents, chicken parvovirus (ChPV), has been suggested to play an important role in MAS; experimental inoculation of birds with ChPV induced clinical signs of the syndrome (Kisary, 1985;Zsak et al., 2013). ...
... As ChPV is not easily isolated in vitro, detection of ChPV in birds has usually been accomplished through searching for viral DNA (Zsak et al., 2013). However, to date, no studies have been conducted attempting to establish correlations between ChPV DNA was extracted from sera, fragments of liver, thymus, spleen and BF. ...
... Among all tissues analyzed, the intestines of MAS-affected broilers contained the highest viral loads (on average up to 5,000 GC/300 ng of DNA). These findings seem to support the suggestion that the primary target cells of ChPV may located in the intestinal tract (Zsak et al., 2013). This finding would not be surprising, since parvoviruses are known to multiply preferentially in fastdividing cells, where these can take full advantage of the ongoing cell multiplication cycle. ...
Article
Malabsorption syndrome (MAS) is a multifactorial syndrome which is characterized by enteric disorders and reduced growth rates of broilers. Such condition is responsible for significant economic losses to the poultry industry. A possible association between chicken parvovirus (ChPV) infections and the occurrence of MAS has been proposed. However, such association has not to date been elucidated in view that ChPV has been detected in healthy as well as in MAS-affected chickens. This study aimed to detect and quantify ChPV loads in sera and tissues of MAS-affected, as well as in healthy broilers. Fifty nine, 39-day-old broilers (50 diseased, 9 healthy birds), obtained from the same flocks, were examined. The highest ChPV DNA loads were detected in MAS-affected broilers, particularly in fecal samples and intestinal tissues (~ 5500 genomic copies/300 ng of total DNA). The average viral genome load in serum in MAS-affected birds was 1134 copies/mL, whereas no viral DNA was found in sera and thymus tissues from healthy animals. These findings reveal that MAS-affected broilers consistently carry ChPV DNA is serum, whereas healthy animals do not. In addition, viral loads in tissues (bursa of Fabricius, spleen, intestine and liver) of MAS-affected birds were significantly higher in comparison to the same tissues from healthy broilers. Although preliminary, the results obtained here indicate an association between the detection of ChPV DNA in serum, in addition to high ChPV viral loads in tissues, and the occurrence of MAS in broilers. Further experiments should be performed to confirm such results.
... Identified in the broiler industry in the 1970s as a transmissible disease of broiler chickens of doubtful etiology [15,[69][70][71], RSS affects very young broiler chickens with characteristic signs that include diarrhea, stunting, and ruffled feathers, leading to significant economic deficits, especially in the broiler industry across the globe [15,25,72]. Several enteric and entero-like viruses have been implicated as the cause of growth issues in chickens with the capability of causing retardation and uneven flock performance [4,14,37,49,62,70,71,73,74]. ...
... Identified in the broiler industry in the 1970s as a transmissible disease of broiler chickens of doubtful etiology [15,[69][70][71], RSS affects very young broiler chickens with characteristic signs that include diarrhea, stunting, and ruffled feathers, leading to significant economic deficits, especially in the broiler industry across the globe [15,25,72]. Several enteric and entero-like viruses have been implicated as the cause of growth issues in chickens with the capability of causing retardation and uneven flock performance [4,14,37,49,62,70,71,73,74]. Although these enteroviruses are associated with growth checks and retardation, not all have been reported to cause RSS in an experimental study. ...
... Although these enteroviruses are associated with growth checks and retardation, not all have been reported to cause RSS in an experimental study. However, reoviruses, parvoviruses, coronaviruses, and astroviruses are known to be the agents of well-defined illnesses and have been demonstrated to cause retardation following oral inoculation in 1-day-old chickens [12,25,45,71,74,75]. As the definitive etiological agent of RSS is still being debated, it appears that an infectious agent is involved and that there is the likely involvement of an RNA virus, considering the varying degree of pathogenicity and retardation in 1-day-old broiler chickens and specific-pathogen-free (SPF) chickens inoculated with CAstV isolates [14,76]. ...
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The chicken astrovirus (CAstV) is a ubiquitous enteric RNA virus that has been associated mainly with conditions, such as the runting-stunting syndrome, severe kidney disease, visceral gout, and white chick syndrome, in broiler-type chickens worldwide. Sequence analysis of the capsid genes’ amino acids of the strains involved in these conditions reveals a genetic relationship and diversity between and within the CAstV genogroups and subgroups based on phylogenetic analysis, genetic distance (p-dist), and pathogenicity. While the two genogroups (A and B) are demarcated phylogenetically, their pairwise amino acid sequence identity is 39% to 42% at a p-dist of 0.59 to 0.62. Group-A consists of three subgroups (Ai, Aii, and Aiii) with an inter- and intra-subgroup amino acid identity of 78% to 82% and 92% to 100%, respectively, and a p-dist of 0.18 to 0.22. On the other hand, the six subgroups (Bi, Bii, Biii, Biv, Bv, and Bvi) in Group-B, with a p-dist of 0.07 to 0.18, have an inter- and intra-subgroup amino acid identity of 82% to 93% and 93% to 100%, respectively. However, these groupings have little to no effect on determining the type of CAstV-associated pathology in chickens.
... ChPV was first reported in 1984 by Kisary et al. (1984), who examined the enteric content of chickens with diarrhea. Experimental studies have revealed that chickens with ChPV exhibit reduced weight gain, dwarfism, and signs of enteric disease, mainly diarrhea (Kisary, 1985;Palade et al., 2011a;Zsak et al., 2013). ChPV primarily affects young chickens, and its replication and pathogenic effects predominate in cells with high proliferative rates (Guy, 1998;Hueffer and Parrish, 2003). ...
... Experimental infection of embryonated eggs with ChPV ABU-1 strain (isolated from chickens with stunted growth) showed a significant reduction in hatchability. In addition, chickens developed enteritis after hatch and showed low vitality, poor feathering, diarrhea, and bone disorders (Kisary, 1985;Zsak et al., 2013). All birds analyzed in the present study showed similar signs, except for bone disorders. ...
... The principal histopathological finding reported in chickens showing signs of LD/MAS was the degeneration of villi, crypts, epithelial cells, and lamina propria in the intestine. In the pancreas the lesions included fibrosis, vacuolization, and degeneration of acinar cells (Qamar et al., 2013;Zsak et al., 2013), similar to the lesions found in experimental infections with CAstV and ANV (Kang et al., 2012). ...
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Enteric disorders are an important cause of economic losses in broiler chickens worldwide. Several agents have been associated with enteric problems, such as viruses, bacteria, and parasites. In this study, broiler chickens showing signs of enteric disorders were subjected to molecular diagnosis for several viral agents and also for pathological examination for elucidating this problem. Thus, the chickens were screened for avian nephritis virus (ANV), chicken astrovirus (CAstV), avian rotavirus (ArtV), avian reovirus (AReoV), infectious bronchitis virus (IBV), fowl adenovirus group I (FAdV-1), and chicken parvovirus (ChPV). Postmortem examinations revealed a curving of the duodenal loop (J-like appearance) and intestines filled with liquid and gaseous content. Histopathological analysis of the duodenal loop showed pancreatic atrophy, acute mesenteritis, and enteritis. PCR results showed that ChPV was the sole viral agent detected in samples with lesions such as the curved duodenal loop and pancreatic atrophy. Molecular characterization of the nucleotide and deduced amino acid sequences revealed a high similarity with other strains of ChPV from Brazil, Canada, United States, Europe, and Asia. These findings suggest an association between ChPV and the development of enteritis, pancreatitis, and pancreatic atrophy, which may lead to curling of the duodenal loop. Together, these alterations may disrupt the normal functioning of the digestive system, diminishing digestion and the absorption of dietary nutrients and consequently leading to reduced weight gain, flock impairment, dwarfism, and an elevated feed conversion rate.
... The viruses commonly associated with poultry enteritis are: Fowl adenovirus-I (FAdV-I), Chicken parvovirus (ChPV), Avian coronavirus (ACV), Chicken astroviruses (CAstV) and Avian nephritis virus (ANV). Avian Reovirus (AReo) and Avian Rotavirus (ARtV) (Zsak et al., 2012;and De la Torre et al., 2018). Enteric viruses are mainly responsible for primary damage to the host tissue which provides opportunity to secondary agent like bacteria (Salmonella, Escherichia coli and Clostridium etc.) or parasite (Eimeria spp.) to invade gastrointestinal tract (GIT) tissue, leading to severe irreversible injury and appearance of clinical signs (Kaithal et al., 2016). ...
... Occurrence of enteric viruses in intestinal contents of broiler chickens at Southern district of RajasthanChicken parvo viruses have also been detected in a high proportion from of chicken flocks suffering from enteritis; this virus can cause growth retardation bed feathering and bone disorders in broilers chickens when experimentally infected(Zsak et al., 2012 andkoo et al., 2013). In this report low prevalence of ChPV (10%) was recorded thanreported from other countries (Koo et al., 2013; Mettifogo et al., 2014 and De la Torre et al., 2018) with prevalence of 26.5%, 12.1% and 6.1% respectively. ...
... The syndrome is also known as infectious stunting syndrome, pale-bird syndrome, malabsorption syndrome, malassimilation, and helicopter disease (Goodwin et al., 1993;Kang et al., 2012Kang et al., , 2018Bulbule et al., 2013;Day and Zsak, 2013;Nuñez and Ferreira, 2013;Smyth, 2017), and was first described by Olsen (1977). The syndrome is characterized in animals by dwarfism, poor development, diarrhea, and mortality (Kang et al., 2012(Kang et al., , 2018Day and Zsak, 2013;Zsak et al., 2013;Domaska-Blicharz et al., 2017). Chicken parvovirus (ChPV), avian rotavirus (ARTv-A), avian reovirus (AReo), chicken astrovirus (CAstV), and avian nephritis virus (ANV) have been detected in the enteric contents of chickens showing enteric diseases (Goodwin et al., 1993;Otto et al., 2006;Pantin-Jackwood et al., 2007Nuñez and Ferreira, 2013;Mettifogo et al., 2014). ...
... This shows the viral diversity and possible viral combinations that could be in the chicken gut, which complicates the study of enteric diseases and syndromes. However, there are studies showing that when a virus is inoculated alone, it produces RSS (Kang et al., 2012(Kang et al., , 2018Zsak et al., 2013). ANV inoculated alone could cause enteric problems (Kang et al., 2012) and could be considered a causative agent of enteric disease, principally a causative agent of RSS. ...
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Runting-stunting syndrome (RSS) is one of the diseases associated with many detected viruses. In Brazil, there were reports of several enteric disease outbreaks in chickens in which avian nephritis virus (ANV) was detected; however, the role of ANV in the outbreaks and whether the virus was a causative agent of these cases of enteric diseases were not determined. The aim of this study was to isolate ANV in specific pathogen-free (SPF) chicken embryonated eggs (CEE) from the enteric contents of chickens showing signs of RSS. For this purpose, 22 samples of chicken enteric contents that were positive only for ANV were inoculated into 7 and 14-day-old SPF-CEE via the yolk sac route and incubated for 5 d, with a total of 3 passages. Virus isolation was confirmed by the presence of embryo injuries, detection of viral RNA by RT-PCR, and visualization of viral particles using electron microscopy. Therefore, the 7-day-old inoculated embryos showed dwarfism, gelatinous consistency, hemorrhage, and edema in the embryos, whereas the 14-day-old did not show any alteration. Viral RNA was detected in the embryos of both ages of inoculation, and the same viral particles were visualized. The embryos from the mock group showed no alteration and were negative for all the tests. The viral cDNA was sequenced, and the molecular and phylogenetic analyses showed that the Brazilian isolates are more related with the ANV-1 serotype group; the sequences of these isolates showed a high percentage of nucleotide (86.4 to 94.9%) and amino acid (92.3 to 98.7%) similarity with other sequences from China, Japan, Australia, and the United States that belong to this serotype previously classified group. In this study, we isolated 8 samples of ANV in SPF-CEE from enteric content samples from chickens with RSS. In doing so, we showed the pathological injuries to the embryo caused by the virus and the molecular characterization of a part of the ORF 1b gene of the virus.
... Intestines of ten flocks with RSS had characteristic gross lesions like pale intestinal wall and most of them had watery contents and gas bubbles (Fig 1). Similar lesions were reported in viral enteritis (McNulty et al. 1983;Zsak, 2013). Gross lesions of individual flocks are shown in Table 1. ...
... Chicken parvovirus was speculated to cause RSS after its initial identification in 1984 from the intestines of RSS/MAS affected chickens (Kisary et al. 1984). Subsequently, several strains are being reported from around the world especially in chicken with enteritis without RSS by researchers such as Zsak et al. (2008), Bidin et al. (2012) and Mettifogo et al. (2014); associated with RSS by Kisary et al. (1984) and Zsak (2013). The occurrence of ChPV in the present study was high when compared to earlier studies by Koo et al. (2013). ...
Article
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Background: Runting-stunting syndrome (RSS) in chickens is a worldwide problem, attributed with several etiological agents. The present study aimed to identify the association of enteric viruses with RSS in different chicken flocks. Methods: Intestinal samples from 14 flocks of chicken of different age and breed and with or without RSS were collected randomly from necropsy samples, isolated nucleic acids, and screened for major enteric viruses by Polymerised chain reaction (PCR), using species-specific primers. Result: Chicken Parvovirus (ChPV) was identified in 100% of the flocks with RSS, in two of which ChPV alone was detected. While in others it was associated with Avian nephritis virus, Avian Rotavirus, Chicken astrovirus, and Fowl adenovirus in 80%, 50%, 30% and 10% flocks, respectively. RSS was reproduced and isolated ChPV by chicken embryo inoculation using the samples from ChPV alone infected cases. Sequence analysis of ChPV revealed closer association with Ecuodor isolates than the Asian isolates. The results indicated the presence of ChPV in Indian chicken flocks and its close association with RSS.
... The viruses commonly associated with poultry enteritis are: Fowl adenovirus-I (FAdV-I), Chicken parvovirus (ChPV), Avian coronavirus (ACV), Chicken astroviruses (CAstV) and Avian nephritis virus (ANV). Avian Reovirus (AReo) and Avian Rotavirus (ARtV) (Zsak et al., 2012;and De la Torre et al., 2018). Enteric viruses are mainly responsible for primary damage to the host tissue which provides opportunity to secondary agent like bacteria (Salmonella, Escherichia coli and Clostridium etc.) or parasite (Eimeria spp.) to invade gastrointestinal tract (GIT) tissue, leading to severe irreversible injury and appearance of clinical signs (Kaithal et al., 2016). ...
... Occurrence of enteric viruses in intestinal contents of broiler chickens at Southern district of RajasthanChicken parvo viruses have also been detected in a high proportion from of chicken flocks suffering from enteritis; this virus can cause growth retardation bed feathering and bone disorders in broilers chickens when experimentally infected(Zsak et al., 2012 andkoo et al., 2013). In this report low prevalence of ChPV (10%) was recorded thanreported from other countries (Koo et al., 2013; Mettifogo et al., 2014 and De la Torre et al., 2018) with prevalence of 26.5%, 12.1% and 6.1% respectively. ...
Research
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Enteric viruses play major role in affecting the poultry industry worldwide, the occurrence of enteric viruses in poultry is still very poorly explored in India. Therefore, a molecular survey has been performed to determine the presence of enteric viruses among enteritis affected poultry flocks of Udaipur and Chittorgarh districts of Southern Rajasthan, India. Total 60 pooled samples of intestine were collected from enteritis affected dead birds, DNA and RNA viruses were detected by PCR and reverse transcriptase PCR respectively. Enteric viruses namely Fowl adenovirus-I(FADV-I), Chicken parvovirus (CPV), Avian coronavirus (ACV), and Chicken astroviruses (CAstV) were detected in 73.32 % of investigated samples. FAdV-I (21.66%) was detected as highest single virus infection followed by ACV (13.33%). Combinations of two or more enteric viruses were simultaneously identified in 38.33% samples.
... Many etiological agents, such as bacteria, fungi, parasites, mycotoxins, and viruses, are related to enteric diseases. Enteric viruses have been considered the main causative etiological agents of RSS and acute enteric disturbances that negatively affect the yield of commercial chickens [1,2,4,22,23]. The most common viruses associated with the enteric diseases of chickens and turkeys include FAdV-I, ChPV, CAstV, ANV, IBV, AReo, and ARtV [7,9]. ...
... FAdV-I was detected in young and old birds (Tables 4 and 5), corroborating results obtained previously [29], where the virus was found in several samples from broilers, layers, and domestic chickens of all ages, even though the clinical signs were more severe in younger birds [30]. ChPV infections affect young birds in their first four weeks [23,27], which is supported by our findings since the virus was detected in 20 infected samples from broilers between 1 and 28 days old (Table 8). AReo was found in 15/333 detections, corresponding to broilers in the growth phase (Table 8), especially between 8 to 28 days old, showing that rotavirus infections mainly affect young birds, promoting RSS and enteric lesions [1]. ...
Article
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Enteric viruses play an important role in the Brazilian poultry industry due to the economic impact of resulting low yields of broilers, layers, and breeders. The most common enteric viruses affecting commercial flocks in Brazil include Fowl Adenovirus of group I (FAdV-I), Chicken Parvovirus (ChPV), Chicken Astrovirus (CAstV), Avian Nephritis Virus (ANV), Infectious Bronchitis Virus (IBV), Avian Reovirus (AReo), and Avian Rotavirus (ARtV). The aim of this study was to identify single and multiple infections using data obtained from 270 samples from eleven Brazilian states, corresponding to the period between 2010 and 2017. This was accompanied by an analysis of the relationship between the age of birds, clinical signs, and geographical distribution, using Polymerase Chain Reaction (PCR) and Reverse Transcription-PCR (RT-PCR) techniques. Twenty-five profiles of virus combinations were detected. Single infections were encountered in 86.3% of samples, and multiple infections were present in the remaining 13.7%. Both single and multiple infections affected all kinds of commercial chickens with digestive problems, stunting syndrome, decreases in egg and meat production, increased mortality, and respiratory signs. FAdV-I, ChPV, CAstV, ANV, and ARtV were mostly detected in young broilers, in contrast with IBV, which was detected in hens from one to greater than 51 weeks of age. These results exhibit the complexity of enteric diseases and the still poorly understood role of each pathogen as a unique etiological agent.
... In the last years, enteric viruses, such as chicken astrovirus (CAstV), chicken parvovirus (ChPV), avian rotavirus (ART), fowl adenovirus type I (FAdV I) and avian reovirus (AReo) have been increasingly implicated. This report is showing its presence alone or in concomitant infections during outbreaks and suggesting that they play an important role in the aetiology of enteric disease (Zsak et al. 2013). These recent reports have led to the development of experimental models to recreate the disease and to try to determine its etiopathogenicity (Zsak et al. 2013, Decaesstecker et al. 1989, Nuñez et al. 2015a). ...
... This report is showing its presence alone or in concomitant infections during outbreaks and suggesting that they play an important role in the aetiology of enteric disease (Zsak et al. 2013). These recent reports have led to the development of experimental models to recreate the disease and to try to determine its etiopathogenicity (Zsak et al. 2013, Decaesstecker et al. 1989, Nuñez et al. 2015a). However, due to the complex nature of this disease, the exact aetiology remains unknown. ...
Article
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Enteric disease is a multifactorial problem in chickens, which causes gastrointestinal alterations, elevated feed conversions and impairment. In the last years, several enteric viruses were implicated in enteric disease; case reports have shown their presence alone or in concomitant infections during outbreaks and have suggested that they might be determining factors in the aetiology of enteric disease. This study shows high detection rates of enteric viruses in the pancreas and spleen in samples from an outbreak of enteritis and malabsorption in 16 chicken flocks (n=80 broilers). Avian nephritis virus (ANV) was the most ubiquitous virus, present in 75% of the flocks followed by avian rotavirus group A (ART-A) with 68.75%, and by chicken astrovirus (CAstV) and chicken parvovirus (ChPV) in 43.75% of samples. Viruses were present in the pancreas of positive flocks at extremely high rates: 100% for ART-A, 91.7% for ANV, 100% for CAstV and 57.14% for ChPV. By contrast, only 16.7% and 57.14% of intestine samples were positive for ANV and CAstV, respectively. Avian reovirus (AReo) and avian adenovirus group 1 (FAdV-1) were not detected. These results suggest that high viral detection rates in pancreas samples may be a result of viremia during enteric disease, with subsequent damage of the exocrine pancreas, leading to runting-stunting syndrome (RSS).
... The ChPV genome consists of a single-stranded linear DNA molecule, 5257 nucleotide (nt) long. It encodes two major proteins: the non-structural (NS) protein, essential for the replication of the viral genome, and a structural viral protein (VP) (Zsak et al. 2013). The NS gene appears to be highly conserved among parvoviruses, and it is often used as target for nucleic acidbased diagnostic tests (Koo et al. 2015;Zsak et al. 2009). ...
Article
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Chicken parvovirus (ChPV) has been associated with malabsorption syndrome (MAS) in broilers. However, the participation of this virus in such syndrome is unclear, since it may be detected in diseased and healthy chickens. In the course of these studies, it was argued whether ChPV genome loads might be correlated to the occurrence of MAS. To check such a hypothesis, a SYBR green-based quantitative polymerase chain reaction was developed to detect and quantify ChPV genomes. Cloacal swabs from 68 broilers with MAS and 59 from healthy animals were collected from different poultry farms. Genomes of ChPV were detected in all samples, regardless of their health status. However, viral genome loads in MAS-affected broilers were significantly higher (1 × 10⁵ genome copies per 100 ng DNA) than in healthy animals (1.3 × 10³ GC/100 ng DNA). These findings indicate that there is an association between high ChPV genome loads and the occurrence of MAS in broilers.
... However, it should be noted, that most of the information about the PV came from studies of birds with enteritis problems. On the other hand, enteritis was experimentally reproduced in chickens infected with intestinal content containing parvoviral particles; however, the used inoculum might have contained other unknown viruses (apart from astrovirus, rotavirus and reovirus tested) which might have caused disease symptoms [24]. Our results identified the presence of PV with the same intensity in healthy individuals as in diseased ones. ...
Article
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Background Enteric diseases are an important health problem for the intensive poultry industry, resulting in considerable economic losses. Apart from such microbiological agents associated with enteritis as bacteria and parasites, a lot of research has been recently conducted on viral origin of enteric diseases. However, enteric viruses have been identified in intestinal tract of not only diseased but also healthy poultry, so their role in enteritis is still unclear. The present study aimed at determination of the prevalence of four enteric viruses, namely astrovirus, coronavirus, parvovirus and rotavirus in meat-type turkey flocks in Poland as well as at statistical evaluation of the occurrence of the studied viruses and their relationships with the health status and the age of birds. Two hundred and seven flocks of birds aged 1-20 weeks originating from different regions of the country were investigated between 2008 and 2011. Clinical samples (10 individual faecal swabs/flock) were duly processed and examined using molecular methods targeting the conservative regions of viral genomes: RNA-dependent RNA polymerase gene of astrovirus, non-structural 1 gene of parvovirus, non-structural protein 4 gene of rotavirus, and 5′ untranslated region fragment of turkey coronavirus. Different statistical methods (i.e. the independence chi-square test, the correspondence analysis and the logistic regression model) were used to establish any relationships between the analyzed data. ResultsOverall, 137 (66.2%, 95% CI: 59.3-72.6) of the 207 turkey flocks sampled were infected with one or more enteric viruses. Among the 137 flocks, 74 (54%, 95% CI: 45.3-62.6) were positive for one virus, whereas 54 (39.4%, 9 5% CI: 31.2-48.1) and 9 (6.6%, 95% CI: 3.1-12.1) were co-infected with two or three different enteric viruses, respectively. No flock was simultaneously infected with all four viruses studied. The prevalence of astrovirus infection was 44.9% (95% CI: 38.0-52.0), parvovirus 27.5% (95% CI: 21.6-34.2), rotavirus 18.8% (95% CI: 13.8-24.8), and coronavirus 9.7% (95% CI: 6.0-14.5). Young turkeys aged 1-4 weeks old had the highest (82.1%, 95% CI:71.7-89.8) prevalence of viral infection. Applied statistical methods have indicated the dependence of rotavirus infection as well as the co-infection with multiple viruses and the health status of turkeys. Furthermore, our results statistically confirm that especially young birds are susceptible to infection with rotavirus and astrovirus. Conclusions The study demonstrated the presence of astrovirus, coronavirus, parvovirus and rotavirus infections in Polish turkey farms. These viruses were detected in both healthy and diseased birds. However, the presented results provide valuable feedback which could help to evaluate the role of some enteric viruses in the etiology of enteritis in turkey.
... Enteric diseases were reported in mammals, and several outbreaks of diarrhea, were associated with enteric viruses, such as astrovirus (Dai et al., 2010;De Benedictis et al., 2011;Zsak et al., 2013), rotavirus (Rajendran and Kang, 2014;Wu et al., 2014), and coronavirus (Costa et al., 2014;Pinto et al., 2014). Chickens and turkeys are also affected by enteric diseases, and outbreaks of enteric diseases have been described in several parts of the world (McNulty et al., 1980a;Pantin-Jackwood et al., 2008;Guy et al., 2011;Day and Zsak, 2013;Nuñez and Piantino Ferreira, 2013a). ...
Article
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Chicken astrovirus (CAstV) is one of many viruses related to enteric diseases in poultry that are associated with Runting-Stunting Syndrome (RSS), which affects young chickens. CAstV was also recently associated with an unusual condition in chicks called “white chicks.” Some hatcheries in certain states of Brazil have reported several incubation problems, mortality, and the presence of chicks with white plumages over the past several months. These chicks were termed locally as “white chicks.” The present work investigated 30 chicks with this unusual condition using a multidisciplinary approach. Postmortem examination of each chick showed enlarged livers and intestines that were full of liquid and gas (30/30). The pancreas, kidneys, and spleen were pale (30/30). The other organs did not show any macroscopic alterations. CAstV, chicken parvovirus (ChPV), avian nephritis virus (ANV), avian rotavirus (ARtV), avian reovirus (AReoV), infectious bronchitis virus (IBV), and fowl adenovirus group I (FAdV-1) were tested in the intestines, pancreas, proventriculus, gizzard, liver, spleen, bursa, kidneys, thymus, lung, heart, brain, and yolk sac in each chick. All organs and yolk sacs were positive for CAstV in different titres and negative for the other tested viruses. The partial molecular characterization of the ORF 1b gene of CAstV using 28 sequences revealed a high similarity of the nucleotides and amino acids with sequences of CAstV from North America, Europe, and Asia, and our CAstV sequences clustered into a unique group that was separate from the other sequences. These results demonstrated that CAstV was associated with the white chick condition in Brazil. The virus was distributed in most organs, including the brain and yolk sac. These results suggest that the virus could be transmitted vertically. The molecular characterization also revealed that the CAstV associated with white chick condition was molecularly related to other CAstV sequences found worldwide.
... Kang et al. (2012) found infection of chicken astrovirus and avian nephritis virus in the case of chicken stunting. Zsak et al. (2013) revealed that chicken parvovirus infection experimentally might cause stunting symptom in young broiler chicken. The result of these studies indicated an essential role of viral infection in chicken stunting symptoms in various regions of the world. ...
Article
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The objective of this study was to identify the five different viral infections including avian influenza, Newcastle disease, avian reovirus, avian encephalomyelitis, and Marek’s disease in the runting-stunting syndrome outbreak in several commercial layer farms in Sukabumi and Tangerang in November 2014 using polymerase chain reaction technique. As results, this study identified mix infection of three viruses in the field samples, including Newcastle disease, reovirus, and avian encephalomyelitis; however, it was negative for avian influenza and Marek’s disease viruses. Subsequently, the inoculation of several samples into embryonated chicken eggs confirmed the growth of these three viruses. As a consequence, disease control management should be conducted in the affected farms by implementing effective biosecurity and vaccination program.
... Virus Research 261 (2019) 9-20 and healthy broilers revealed no statistically significant differences. Other authors have proposed associations between these viruses and MAS Zsak et al., 2013). The finding reported here indicate no association between the occurrence of MAS and such agents, therefore providing evidence in support that these viruses are part of normal intestinal microbiota. ...
Article
Malabsorption syndrome (MAS) is an economically important disease of young, commercially reared broilers, characterized by growth retardation, defective feather development and diarrheic faeces. Several viruses have been tentatively associated to such syndrome. Here, in order to examine potential associations between enteric viruses and MAS, the faecal viromes of 70 stool samples collected from diseased (n = 35) and healthy (n = 35) chickens from seven flocks were characterized and compared. Following high-throughput sequencing, a total of 8,347,319 paired end reads, with an average of 231 nt, were generated. Through analysis of de novo assembled contigs, 144 contigs > 1000 nt were identified with hits to eukaryotic viral sequences, as determined by GenBank database. A number of known and unknown representatives of Adenoviridae, Anelloviridae, Astroviridae, Caliciviridae, Circoviridae, Parvoviridae, Picobirnaviridae, Picornaviridae and Reoviridae, as well as novel uncharacterized CRESS-DNA viruses, were identified. However, the distribution of sequence reads of viral genomes identified in diseased or healthy birds revealed no statistically significant differences. These findings indicate no association between the occurrence of MAS and enteric viruses. The viral genomes reported in the present study, including a variety of novel viruses, seem part of the normal intestinal microbiota of chickens.
... Several reports associating enteric viruses with RSS or poor poultry performance in different parts of the world have been made (Kang et al. 2012;Bulbule et al. 2013;Zsak et al. 2013;Nuñez et al. 2016;Xue et al. 2017;Adebiyi et al. 2019). CAstV and ANV have been largely incriminated in growth depression including RSS and uneven growth in poultry worldwide, indicating the geographical spread of these viruses. ...
Article
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Infections with divergent strains of astroviruses appear to be endemic in commercial poultry. In order to investigate enteric viruses associated with hatchery condemnations in Nigerian poultry, an indirect immunofluorescence test with CAstV-612- (Group A), CAstV-11672- (Group B) and ANV-1-infected cells was used to screen sera obtained from commercial broilers (n = 164) and turkeys (n = 97) in farms and hatcheries in southwest Nigeria. Of the 261 sera tested, 16 (6.1%) were positive for CAstV antibodies after immunofluorescent staining with CAstV-11672-infected cells. Thirteen (81.3%) of the positive sera were from broilers with three (18.7%) being from turkeys. Conversely, all tested sera were negative for CAstV-612 and ANV-1 antibodies. Since CAstV-11672, a group B CAstV is known to be antigenically and genetically distinct from CAstV-612 that belongs to group A, these findings reveal that the circulating serotype of CAstV in commercial broilers and turkeys in southwest Nigeria belongs to group B of CAstV. Education of veterinary personnel and poultry farmers about this emerging virus and its impact on commercial poultry in Nigeria, as well as continuous monitoring of chicken and turkey flocks for infections caused by it are therefore imperative in order to facilitate the implementation of effective prevention and control measures.
... Despite much research have been conducted to elucidate the etiology of RSS, it remains unclear. A large and growing number of viral pathogens and even a combination of multiple viruses have been associated with RSS in broiler chickens, such as reovirus (Songserm et al. 2002), astrovirus (Kang et al. 2012), rotavirus , calicivirus (Devaney et al. 2016), coronavirus (Hauck et al. 2016), parvovirus (Zsak et al. 2013), birnavirus (Noiva et al. 2015), and gallivirus (Oliveira et al. 2021). Because we did not investigate other pathogens, our findings are not sufficient to establish a causal relationship between AvRV and RSS. ...
Article
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The aim of this study was to investigate and compare the frequency of occurrence of avian rotavirus (AvRV) in poultry flocks according to its Performance Efficiency Index (PEI) scores. A total of 256 individual intestinal content samples of small sized-chicks (runts) with clinical signs of Runting Stunting Syndrome (RSS) and 24 clinically healthy chicks (control) were collected from twelve flocks in southern Brazil with different PEI scores: good (n = 4, PEI mean = 365); moderate (n = 4, PEI mean = 342) or poor (n = 4, PEI mean = 319). Silver-stained polyacrylamide gel electrophoresis (ss-PAGE) was used to detect and identify the AvRV species followed by RT-PCR and sequencing of the partial VP6 gene for species confirmation. AvRV was detected in 83% (10/12) of the flocks and 23.4% (60/256) of the chicks. The electrophoretic migration patterns of viral dsRNA segments were compatible with AvRV species A (AvRV- A), D (AvRV-D) and F (AvRV-F) in 9 (15%), 18 (30%), and 33 (55%) of the positive chicks fecal samples, respectively. The AvRV species identified by ss-PAGE were confirmed by RT-PCR and partial sequence analysis of the VP6 gene. The AvRV detection rate was statistically higher (p = 0.007) in chicks from flocks with poor PEI when compared to those with good PEI. The occurrence of AvRV-D and AvRV-F was statistically higher in 7 to 9 days old chicks, while AvRV-A was detected only in 13 to 14 days old animals.
... In fact, in order to reproduce the full complement of enteric signs observed in these syndromes, transmission studies have relied upon the administration of crude, uncharacterized intestinal homogenates prepared from affected birds, or by placing healthy birds on the litter previously used to rear affected flocks [13]. Many investigations have focused on individual intestinal viruses as possible etiologic agents in PEC and RSS [14][15][16][17][18], with many RNA viruses such as members of the Astroviridae and Reoviridae being implicated. To further complicate any investigation, suspect enteric viruses implicated in these syndromes are also often found in healthy poultry flocks, and pathogenic bacterial and even protozoal infections may be present in certain cases [1,9]. ...
Article
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There is a great deal of interest in characterizing the complex microbial communities in the poultry gut, and in understanding the effects of these dynamic communities on poultry performance, disease status, animal welfare, and microbes with human health significance. Investigations characterizing the poultry enteric virome have identified novel poultry viruses, but the roles these viruses play in disease and performance problems have yet to be fully characterized. The complex bacterial community present in the poultry gut influences gut development, immune status, and animal health, each of which can be an indicator of overall performance. The present metagenomic investigation was undertaken to provide insight into the colonization of specific pathogen free chickens by enteric microorganisms under field conditions and to compare the pre-contact intestinal microbiome with the altered microbiome following contact with poultry raised in the field. Analysis of the intestinal virome from contact birds ("sentinels") placed on farms revealed colonization by members of the Picornaviridae, Picobirnaviridae, Reoviridae, and Astroviridae that were not present in pre-contact birds or present in proportionally lower numbers. Analysis of the sentinel gut bacterial community revealed an altered community in the post-contact birds, notably by members of the Lachnospiracea/Clostridium and Lactobacillus families and genera. Members of the avian enteric Reoviridae and Astroviridae have been well-characterized and have historically been implicated in poultry enteric disease; members of the Picobirnaviridae and Picornaviridae have only relatively recently been described in the poultry and avian gut, and their roles in the recognized disease syndromes and in poultry performance in general have not been determined. This metagenomic analysis has provided insight into the colonization of the poultry gut by enteric microbes circulating in commercial broiler flocks, and has identified enteric viruses and virus communities that warrant further study in order to understand their role(s) in avian gut health and disease.
Chapter
Enteric viruses are commonly the cause of most of the primary insults to the gastrointestinal tract of young poultry. This chapter offers detailed coverage of the history, etiology, pathobiology, epizootiology, diagnosis, and intervention strategies of various viral enteric infections. The turkey coronavirus genome consists of a linear, non‐segmented, single stranded RNA molecule that is approximately 28 kilobases in size. Rotaviruses are excreted in avian feces, and can be readily detected in cloacal swabs using molecular diagnostics. Astroviruses are the most common viruses associated with poult enteritis complex, poult enteritis syndrome, and poult enteritis and mortality syndrome in turkeys. Diagnosis of enterovirus‐like virus infections in avian species most commonly is accomplished by transmission electron microscopy examination of droppings or intestinal samples. Conventional or real‐time polymerase chain reaction assays targeting specific chicken or turkey parvovirus genes have implicated parvovirus in outbreaks of enteritis, and are a useful tool for experimental diagnosis.
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Parvoviruses are commonly found in U.S. poultry and are associated with clinical disease. Here, we report the complete coding sequences of three chicken parvoviruses from broiler chickens from commercial farms in the state of Georgia.
Article
Runting stunting syndrome (RSS) in commercial chickens has been reported worldwide, and although several studies have attempted to clarify the cause and describe the lesions, there are gaps in knowledge of the epidemiology, pathogenesis, and etiology. The study objective was to use commercial chicks naturally affected by RSS to describe the histologic changes of RSS in all segments of the small intestine in chicks of different ages and to identify viral gene sequences in affected chicks and their association with histologic lesions. Chicks lacking clinical signs but from the same houses and from unaffected houses were used as controls. The average weight of affected chicks was significantly lower than expected for their flocks. Macroscopically, the small intestines had paler serosa, with watery, mucoid, or foamy contents and poorly digested food. Histologic lesions were characterized by necrotic crypts, crypt dilation, and flattening of the crypt epithelium. Histomorphometry of the intestines revealed villous atrophy especially in the jejunum and ileum. Histologic changes in other organs were not observed. Random next-generation sequencing of total RNA extracted from formalin-fixed paraffin-embedded tissues detected avian nephritis virus, avian rotavirus, and picornavirus in jejunal segments from 7-day-old chicks. No viruses were detected in the jejunum of 1-day-old chicks. Detection of picornaviral reads was significantly associated ( P < .05) with histologic lesions of RSS. Sequence analysis of the picornavirus revealed genetic similarity with the genus Gallivirus. Using in situ hybridization for galliviral nucleic acid sequences, the signal was associated with crypt lesion severity, although signal was detected both in chicks with and without RSS.
Article
Runting stunting syndrome (RSS) is a disease condition that affects broilers and causes impaired growth and poor feed conversion because of enteritis characterized by pale and distended small intestines with watery contents. The etiology of the disease is multifactorial, and a large variety of viral agents have been implicated. Here we describe the detection and isolation of an infectious bronchitis virus (IBV) -like coronavirus from the intestines of a flock of 60,000 14-day-old brown/red broiler chicks. The birds showed typical clinical signs of RSS including stunting and uneven growth. At necropsy, the small intestines were pale and distended with watery contents. Histopathology of the intestines revealed increased cellularity of the lamina propria, blunting of villi, and cystic changes in the crypts. Negative stain electron microscopy of the intestinal contents revealed coronavirus particles. Transmission electron microscopy of the intestine confirmed coronavirus in the cytoplasm of enterocytes. Using immunohistochemistry (IHC), IBV antigen was detected in the intestinal epithelial cells as well as in the proventriculus and pancreas. There were no lesions in the respiratory system, and no IBV antigen was detected in trachea, lung, air sac, conjunctiva, and cecal tonsils. A coronavirus was isolated from the intestine of chicken embryos but not from the allantoic sac inoculated with the intestinal contents of the broiler chicks. Sequencing of the S1 gene showed nucleic acid sequence identities of 93.8% to the corresponding region of IBV California 99 and of 85.7% to IBV Arkansas. Nucleic acid sequence identities to other IBV genotypes were lower. The histopathologic lesions in the intestines were reproduced after experimental infection of specific-pathogen-free chickens inoculated in the conjunctiva and nares. Five days after infection, six of nine investigated birds showed enteritis associated with IBV antigen as detected by IHC. In contrast to the field infection, birds in the experimental group showed clear respiratory signs and lesions in the upper respiratory tract. The results suggest a broader tissue tropism of this isolate, which might be related to the mutations in the S1 gene.
Article
Runting Stunting Syndrome (RSS) is a disease condition that affects broilers and causes impaired growth and poor feed conversion due to enteritis characterized by pale and distended small intestines with watery contents. The etiology of the disease is multifactorial and a large variety of viral agents have been implicated. Here we describe the detection and isolation of an infectious bronchitis virus (IBV) -like coronavirus from the intestines of a flock of 60,000 14 days-old Brown/Red broiler chicks. The birds showed typical clinical signs of RSS including stunting and uneven growth. At necropsy, the small intestines were pale and distended with watery contents. Histopathology of the intestines revealed increased cellularity of the lamina propria, blunting of villi and cystic changes in the crypts. Negative stain electron microscopy of the intestinal contents revealed coronavirus particles. Transmission electron microscopy of the intestine confirmed coronavirus in the cytoplasm of enterocytes. Using immunohistochemistry (IHC), IBV antigen was detected in the intestinal epithelial cells as well as in the proventriculus and pancreas. There were no lesions in the respiratory system and no IBV antigen was detected in trachea, lung, air sac, conjunctiva and cecal tonsils. A coronavirus was isolated from the intestine of chicken embryos but not from the allantoic sac inoculated with the intestinal contents of the broiler chicks. Sequencing of the S1 gene showed nucleic acid sequence identities of 93.8% to the corresponding region of IBV California 99 and of 85.7% to IBV Arkansas. Nucleic acid sequence identities to other IBV genotypes were lower. The histopathological lesions in the intestines were reproduced after experimental infection of specific pathogen free (SPF) chickens inoculated in the conjunctiva and nares. Five days after the infection six of nine investigated birds showed enteritis associated with IBV antigen as detected by IHC. In contrast to the field infection, birds in the experimental group showed clear respiratory signs and lesions in the upper respiratory tract. The results suggest a broader tissue tropism of this isolate, which might be related to the mutations in the S1 gene.
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Runting stunting syndrome (RSS) in broiler chickens is characterized by altered intestinal morphology and gene expression and stunted growth. The objective of this study was to conduct a retrospective study of gene expression in stem and differentiated cells in the small intestine of RSS chicks. Two different models of RSS were analyzed: broiler chicks that were experimentally infected and broiler chicks that were naturally infected. Experimentally infected chicks were exposed to litter from infected flocks (RSS-litter chicks) or infected with astrovirus (RSS-astrovirus chicks). Intestinal samples from naturally infected chicks showing clinical signs of RSS were acquired from commercial farms in Georgia and were brought into a poultry diagnostic lab (RSS-clinical-GA) and from farms in Brazil that had a history of RSS (RSS-clinical-BR). The RSS-clinical-BR chicks were separated into those that were positive or negative for gallivirus based on DNA sequencing. Intestinal morphology and intestinal cell type were identified in archived formalin-fixed, paraffin-embedded tissues. In situ hybridization for cell-specific mRNA was used to identify intestinal stem cells expressing olfactomedin 4 (Olfm4), proliferating cells expressing Ki67, absorptive cells expressing sodium glucose cotransporter 1 (SGLT1) and peptide transporter 1 (PepT1), and goblet cells expressing mucin 2 (Muc2). RSS-litter and RSS-clinical-GA chicks showed 4% to 7.5% cystic crypts, while gallivirus-positive RSS-clinical-BR chicks showed 11.7% cystic crypts. RSS-astrovirus and gallivirus-negative RSS-clinical-BR chicks showed few cystic crypts. RSS-litter and gallivirus-positive RSS-clinical-BR chicks showed an increase in crypt depth compared to control or gallivirus-negative chicks, respectively. There was no expression of Olfm4 mRNA in the stem cells of RSS-litter and RSS-clinical-GA chicks, in contrast to the normal expression of Olfm4 mRNA in RSS-astrovirus and RSS-clinical-BR chicks. All chicks regardless of infection status showed normal expression of Ki67 mRNA in crypt cells, Muc2 mRNA in goblet cells, and SGLT1 or PepT1 mRNA in enterocytes. These results demonstrate that RSS, which can be induced by different etiologies, can show differences in the expression of the stem cell marker Olfm4.
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Runting-stunting syndrome (RSS) in broiler chickens is an enteric disease that causes significant economic losses to poultry producers worldwide due to elevated feed conversion ratios, decreased body weight during growth, and excessive culling. Of specific interest are the viral agents associated with RSS which have been difficult to fully characterise to date. Past research into the aetiology of RSS has implicated a wide variety of RNA and DNA viruses however, to date, no individual virus has been identified as the main agent of RSS and the current opinion is that it may be caused by a community of viruses, collectively known as the virome. This paper attempts to characterise the viral pathogens associated with 2 – 3 week old RSS-affected and unaffected broiler chickens using next-generation sequencing and comparative metagenomics. Analysis of the viromes identified a total of 20 DNA & RNA viral families, along with 2 unidentified categories, comprised of 31 distinct viral genera and 7 unclassified genera. The most abundant viral families identified in this study were the Astroviridae, Caliciviridae, Picornaviridae, Parvoviridae, Coronaviridae, Siphoviridae, and Myoviridae. This study has identified historically significant viruses associated with the disease such as chicken astrovirus, avian nephritis virus, chicken parvovirus, and chicken calicivirus along with relatively novel viruses such as chicken megrivirus and sicinivirus 1 and will help expand the knowledge related to enteric disease in broiler chickens, provide insights into the viral constituents of a healthy avian gut, and identify a variety of enteric viruses and viral communities appropriate for further study.
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Astroviruses have been associated with enteric and extra-intestinal disorders in many animal species, including chickens. Here, we describe the detection and characterisation of chicken astrovirus (CAstV) in broilers and its seroprevalence in broiler breeder flocks. Based on PCR protocol, viral confirmation was carried out on clinical tissue samples from broiler chickens suffering from uneven growth and poor performance. The tissues were molecularly detected for CAstV with differential diagnostic testing against the Newcastle disease virus, infectious bronchitis virus, avian nephritis virus, avian rotavirus, fowl adenovirus and avian reovirus. Polymerase gene-based phylogenetic analyses of the twenty samples detected positive for CAstV indicate they belong to Group I and are related to strains from the US, UK, India and Poland. From these 20 samples, CastV could be isolated from 3 samples upon inoculation in 5-day-old specific-pathogen-free (SPF) embryonated chicken eggs (ECE); virus-infected embryos showed dwarfing, haemorrhages, oedema and gelatinous lesions at harvest. The enzyme-linked immunosorbent assay (ELISA) Pertanika results revealed a high prevalence of antibodies against CAstV amongst the broiler breeder flocks tested. It is the first study that describes the detection and prevalence of CAstV in broiler chickens and broiler breeder flocks in Malaysia.
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SUMMARY This report describes an outbreak of transmissible viral proventriculitis (TVP) associated with runting stunting syndrome (RSS) in 25- and 28-day-old broiler chickens, in which chicken proventricular necrosis virus (CNPV) was detected. Clinical signs included poor uniformity, very small birds for their age, increased mortality, and culling of smaller birds. Almost all birds necropsied exhibited moderate to severely enlarged proventriculi with diffusely pale serosa and thickened walls. Microscopically the proventriculi had lesions of degeneration and necrosis of the epithelium of the proventricular glands, accompanied by lymphocytic inflammation and glandular hyperplasia, with occasional formation of lymphoid nodules within the glandular parenchyma. Immunohistochemistry staining for CPNV was positive. Positive staining was generally found in the cytoplasm of glandular epithelial cells in the form of finely granular brown pigment. CPNV RNA was detected in the proventriculi by reverse transcriptase–PCR (RT-PCR). Other findings included mild enteritis in a few birds and small bursa of Fabricius. Direct electron microscopy performed on the intestinal samples was negative for viral particles. RT-PCR analysis of bursae was positive for infectious bursal disease virus (IBDV). In conclusion, this report associates TVP with RSS by describing an outbreak in which TVP attributable to CPNV was the most commonly found lesion in chickens with a clinical history compatible with RSS. Therefore, TVP should be considered as a possible differential diagnosis in cases compatible with RSS.
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RESUMEN Nota de Investigación- Especificidad de hospedador y relaciones filogenéticas de parvovirus de pollos y pavos. La inoculación de pollos y pavos libres de patógenos específicos con cinco parvovirus de pollo (ChPV) y cinco parvovirus de pavo (TuPV) dio lugar a la replicación viral productiva únicamente en la especie hospedadora homóloga. El árbol filogenético basado en las secuencias de nucleótidos del segmento del gene VP1 reveló una agrupación de las cepas virales específica de hospedador. Estos resultados sugieren que el gene VP1 juega un papel esencial en la especificidad del hospedador de las cepas de parvovirus de pollo y de pavo y podría ser una secuencia blanco relevante para la clasificación de las cepas.
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Currently, the aetiology of runting and stunting syndrome (RSS) in chickens is unknown. The impact of RSS on weight gain and microscopic lesions in immunological organs and the duodenum, was investigated in 1-day-old commercial broilers at 12 days following exposure to RSS-contaminated litter. Furthermore, the presence of the viral nucleic acids of three astroviruses and one parvovirus was analysed by in situ hybridization from days 1 through 5 post exposure. A 70% decrease in weight was observed in the RSS-exposed group at the end of the experiments when compared with the unexposed controls. Lesions in the bursa of Fabricius and thymus were present in both groups but were significantly higher at the end of the study in the RSS-exposed group. In contrast, no significant difference in Harderian gland lesions was observed between the groups. Histological lesions in the duodenum were already present 24 h after exposure in the RSS-exposed group only, peaked at day 4 and declined until the end of the study. Results of the in situ hybridization studies clearly indicate replication of three astroviruses (chicken astrovirus, avian nephritis virus [ANV]-1, ANV-2) in the duodenum but not in other organs evaluated. Chicken astrovirus nucleic acids were detected on days 1 and 2 post exposure, while ANV-1 and ANV-2 nucleic acids were observed on several days during the period investigated. Surprisingly, no viral nucleic acid specific for the chicken parvovirus was observed. The results indicate that astroviruses probably play an important role during RSS due to the concurrence of viral RNA detection and lesions in the duodenum.
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The aim of the foregoing study was the determination of the occurrence of parvovirus in chicken flocks from different regions of Poland during 2002-2011. The material used for this study originated from chickens showing clinical symptoms of stunting and emaciation. For the quick detection of genetic material of the viruses in field samples, real-time PCR was applied. The conducted study implied on the occurrence of parvoviral infections in Poland in approximately 18% of investigated chicken flocks. However, their exact role remains still unknown.
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Phylogenetic diversity of parvovirus detected in commercial chicken and turkey flocks is described. Nine chicken and six turkey flocks from Croatian farms were tested for parvovirus presence. Intestinal samples from one turkey and seven chicken flocks were found positive, and were sequenced. Natural parvovirus infection was more frequently detected in chickens than in turkeys examined in this study. Sequence analysis of 400 nucleotide fragments of the nonstructural gene (NS) showed that our sequences had more similarity with chicken parvovirus (ChPV) (92.3%-99.7%) than turkey parvovirus (TuPV) (89.5%-98.9%) strains. Phylogenetic analysis grouped our sequences in two clades. Also, the higher prevalence of ChPV than TuPV in tested flocks was defined. The necropsy findings suggested a malabsorption syndrome followed by a preascitic condition. Further research of parvovirus infection, pathogenesis, and the possibility of its association with poult enteritis and mortality syndrome (PEMS) and runting and stunting syndrome (RSS) is needed to clarify its significance as an agent of enteric disease.
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To identify attributes of zoological institutions and surveillance system factors that were associated with participation in the West Nile Virus Surveillance System for Zoological Institutions in the USA, and to assess the potential effectiveness of zoos as a novel data source for surveillance of emerging infectious zoonoses. Retrospective. The number of specimens submitted between August 2001 and December 2006 for West Nile virus testing was determined for each institution. Descriptive statistics were used to summarize the distribution of number of specimens submitted and features of the institutions. Student's t-test was used to assess potential associations between institutional and animal collection characteristics and the total number of specimens submitted by each institution. Factors associated with institutional participation include: submitting specimens for specific purposes of serosurvey testing, sentinel surveillance, vaccine titre checks, vaccine effectiveness, submitting specimens for multiple reasons, and communication with public health. Understanding how zoo and surveillance system characteristics are associated with participation in this surveillance effort may enhance public health efforts and the design of future zoological surveillance efforts.
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The major enteric disease (ED) complex in broiler chickens is runting-stunting syndrome and in turkey broilers is poult enteritis mortality syndrome. Viruses from numerous families have been identified in the intestinal tracts of poultry with ED, such as Astroviridae, Coronaviridae, Reoviridae, Rotaviridae, and Parvoviridae. The objective of the present study was to directly demonstrate the presence of the scarcely known chicken parvovirus (ChPV) and turkey parvovirus (TuPV) in Hungarian flocks experiencing clinical signs of ED. ChPV and TuPV infection were demonstrated in 15 chicken flocks and two turkey flocks, in intestinal samples collected between 2008 and 2010. The histopathological investigation revealed enteritis in the duodenum and jejunum, and atrophy of the lymphoid organs. Indirect immunohistochemistry (IHC) suggested the intestinal epithelium of chickens and turkeys as a potential replication site of the virus, similarly to other parvoviruses, while in case of the turkey samples IHC positivity was also observed in the bursa of Fabricius, liver and pancreas. However, no direct connection could be established between the presence of the pathogen in the above-mentioned tissues and the histopathological changes observed in the investigated flocks. The phylogenetic analysis performed on the partial nucleic acid sequence of the NS1 gene revealed an evident clustering tendency of the ChPV and TuPV strains, but also highlighted the potential reciprocal role of these two species in the epidemiology of these viruses. The role of the ChPV and TuPV in the ED is far from understood, but the results of the present study emphasize the fact that in certain, still not fully elucidated conditions, ChPV and TuPV may participate in the emergence of ED in chicken flocks, as suggested by previous experimental infections.
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Infection by human parvovirus B19 is widespread and can be associated with a wide range of different pathologies and clinical manifestations. We provide the first evidence of localization of an active parvovirus B19 infection in the intestinal mucosa and its association with a severe inflammatory bowel disease, characterized by duodenal villous atrophy with increased intraepithelial lymphocytes and inflammatory infiltrates in the colonic mucosa. Virus in the intestinal mucosa was detected in cells of the inflammatory infiltrate, identified as T lymphocytes and selectively localized in sites of active tissue degeneration.
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Several different viruses have been identified as causes of gastrointestinal tract infections in poultry. These include rotaviruses, coronaviruses, enteroviruses, adenoviruses, astroviruses, and reoviruses. In addition, a number of other viruses of unknown importance have been associated with gastrointestinal diseases in poultry based on electron microscopic examination of feces and intestinal contents. Viral infections of the gastrointestinal tract of poultry are known to negatively impact poultry production, and they likely contribute to the development of other, extragastrointestinal diseases. Our current understanding of the viruses that cause gastrointestinal tract infections in poultry is reviewed, with emphasis given to those of greatest importance.
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Astroviruses are known to cause enteric disease in several animal species, including turkeys. However, only human astroviruses have been well characterized at the nucleotide level. Herein we report the nucleotide sequence, genomic organization, and predicted amino acid sequence of a turkey astrovirus isolated from poults with an emerging enteric disease.
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An immunohistochemical staining technique (IHC) was developed to detect avian pneumovirus (APV) antigen in formalin-fixed, paraffin-embedded tissue sections using streptavidin-biotin immunoperoxidase staining. Samples of nasal turbinates and infraorbital sinuses were collected from 4-week-old poults experimentally inoculated with APV and from older turkeys infected during naturally occurring outbreaks of avian pneumovirus. Tissue was fixed in 10% buffered neutral formalin, embedded in paraffin, sectioned and stained. Inflammatory changes were observed microscopically in the mucosa and submucosa of the nasal turbinates and infraorbital sinuses of both experimentally inoculated poults and naturally infected birds. Viral antigen was detected by IHC in the ciliated epithelial cells of nasal turbinates and infraorbital sinuses.
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Sequence data was obtained from the capsid (ORF-2) and the polymerase (ORF-lb) genes of 23 turkey astrovirus (TAstV) isolates collected from commercial turkey flocks around the United States between 2003 and 2004. A high level of genetic variation was observed among the isolates, particularly in the capsid gene, where nucleotide sequence identity among them was as low as 69%. Isolates collected on the same farm, on the same day, but from different houses could have as little as 72% identity between their capsid gene sequences when compared. Phylogenetic analysis of the capsid gene revealed no clear assortment by geographic region or isolation date. The polymerase gene was more conserved with between 86 and 99% nucleotide identity and did assort in a geographic manner. Based on differing topologies of the capsid and polymerase gene phylogenetic trees, TAstV appears to undergo recombination.
Feline panleukopenia virus (FPV) and canine parvovirus (CPV) are autonomous parvoviruses which infect cats or dogs, respectively. Both viruses cause an acute disease, with virus replicating for less than seven days before being cleared by the developing immune responses. The viruses have a broad tropism for mitotically active cells. In neonatal animals the viruses replicate in a large number of tissues, and FPV infection of the germinal epithelium of the cerebellum leads to cerebellar hypoplasia, while CPV may infect the hearts of neonatal pups, causing myocarditis. In older animals the virus replicates systemically, primarily in the primary and secondary lymphoid tissues, and also in the rapidly replicating cells of the small intestinal epithelial crypts. A transient panleukopenia or relative lymphopenia is often observed after FPV or CPV infection, respectively. Whether the reduction in cell numbers in vivo is due to virus replicating in and killing cells, or due to other indirect effects, is not known. However, FPV kills both erythroid and myeloid colony progenitors in in vitro bone marow cultures, and it has been suggested that virus replication in the myeloid cells in vivo could lead to the reduced neutrophil levels seen after FPV infection of cats.
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Intestinal samples collected from 43 commercial broiler and 33 commercial turkey flocks from all regions of the United States during 2005 and 2006 were examined for the presence of astrovirus, rotavirus, reovirus, and coronavirus by reverse transcription-polymerase chain reaction (PCR), and for the presence of groups 1 and 2 adenovirus by PCR. Phylogenetic analysis was performed to further characterize the viruses and to evaluate species association and geographic patterns. Astroviruses were identified in samples from 86% of the chicken flocks and from 100% of the turkey flocks. Both chicken astrovirus and avian nephritis virus (ANV) were identified in chicken samples, and often both viruses were detected in the same flock. Turkey astrovirus type-2 and turkey astrovirus type-1 were found in 100% and 15.4% of the turkey flocks, respectively. In addition, 12.5% of turkey flocks were positive for ANV. Rotaviruses were present in 46.5% of the chicken flocks tested and in 69.7% of the turkey flocks tested. Based upon the rotavirus NSP4 gene sequence, the chicken and turkey origin rotaviruses assorted in a species-specific manner. The turkey origin rotaviruses also assorted based upon geographical location. Reoviruses were identified in 62.8% and 45.5% of chicken and turkey flocks, respectively. Based on the reovirus S4 gene segment, the chicken and turkey origin viruses assorted separately, and they were distinct from all previously reported avian reoviruses. Coronaviruses were detected in the intestinal contents of chickens, but not turkeys. Adenoviruses were not detected in any chicken or turkeys flocks. Of the 76 total chicken and turkey flocks tested, only three chicken flocks were negative for all viruses targeted by this study. Most flocks were positive for two or more of the viruses, and overall no clear pattern of virus geographic distribution was evident. This study provides updated enteric virus prevalence data for the United States using molecular methods, and it reinforces that enteric viruses are widespread in poultry throughout the United States, although the clinical importance of most of these viruses remains unclear.
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Astroviruses are frequently associated with enteric diseases in poultry, being isolated from cases of runting-stunting syndrome (RSS) of broiler chickens, poult enteritis complex (PEC), and poult enteritis mortality syndrome (PEMS) of turkeys. Currently, five types of avian astrovirus have been identified: turkey astroviruses 1 and 2 (TAstV-1, TAstV-2), avian nephritis virus (ANV), chicken astrovirus (CAstV) and duck astrovirus (DAstV). The objective of this study was to molecularly characterize the different types of avian astroviruses circulating in commercial poultry. Sequence analysis of a region of ORF2, which encodes the capsid precursor protein associated with serotype and viral pathogenesis, revealed extensive variation in amino acid sequence within each subtype: TAstV-2 (81.5%-100%), ANV (69.9%-100%), and CAstV (85.3%-97.9%). However, this region was more conserved in TAstV-1's (96.2%-100%). Furthermore, a novel astrovirus was detected in chicken samples and found to be <64% similar to ANV and <30.6% similar to CAstV. The results of this study underline the great genetic variability of avian astroviruses and indicate that there are most likely multiple serotypes of each avian astrovirus circulating in commercial poultry.
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Viral enteric disease in poultry is an ongoing problem in many parts of the world. Many enteric viruses have been identified in turkeys and chickens, including avian astroviruses, rotaviruses, reoviruses, and coronaviruses. Through the application of a molecular screening method targeting particle-associated nucleic acid (PAN), we recently described the detection and partial characterization of a novel enteric parvovirus in chickens. Subsequent surveys of intestinal homogenates from turkeys and chickens in the United States revealed widespread occurrence of parvovirus in poultry. Here we report the first full genome sequence of a novel chicken parvovirus, ChPV ABU-P1. ChPV ABU-P1 genome organization, predicted amino acid sequence, and phylogenetic relationships with other described parvoviruses are discussed.
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Here we report the development and application of an enzyme-linked immunosorbent assay (ELISA) to detect parvovirus-specific antibodies in chicken sera. We used an approach previously described for other parvoviruses to clone and express viral structural proteins in insect cells from recombinant baculovirus vectors. In baculovirus recombinant-infected Sf9 cells, the chicken parvovirus (ChPV) structural viral protein 2 (VP2) was detected as an abundant protein, and the 60-kDa VP2 strongly reacted with parvovirus-infected chicken serum in Western blot. A semipurified VP2 was then used in capture ELISA. Sera from chickens experimentally infected with ChPV and sera from uninfected chickens were tested to evaluate the assay. The ELISA was 93.3% sensitive and 100% specific in detecting ChPV-infected birds. Subsequent assays identified IgG type ChPV-specific maternally acquired antibodies in day-old chickens and demonstrated the production of virus-specific antibodies in young birds following infection with ChPV. In our study, a specific antibody response of infected chickens was observed starting with IgM production between 14 and 21 days postinfection (DPI) and switching into a predominant IgG response by 32 DPI. The availability of an ELISA for detection of virus-specific antibodies and its ability to differentiate between maternally acquired antibodies and antibodies produced following acute infection could prove to be a valuable tool to characterize pathobiological properties and immunogenicity of ChPV.
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Comparative sequence analysis of six independent chicken and turkey parvovirus nonstructural (NS) genes revealed specific genomic regions with 100% nucleotide sequence identity. A polymerase chain reaction (PCR) assay with primers targeting these conserved genome sequences proved to be highly specific and sensitive to detecting parvoviruses in experimentally infected chickens. In a nationwide survey, a total of 138 field enteric samples from poultry flocks were tested by PCR for parvovirus presence. Of the tested chicken samples that were collected in 54 farms, 77% showed the presence of parvovirus, while 78% of the turkey samples that were received from 29 farms were parvovirus positive. For the first time, our data clearly demonstrate that parvoviruses are widely distributed in commercial poultry flocks in the United States. The high prevalence of parvovirus infection in birds from enteric disease-affected flocks suggests a potential role of these viruses in the etiology of enteric disease of poultry. Phylogenetic analyses comparing NS gene segments showed that most of the chicken and turkey parvovirus isolates formed separate phylogenetic groups. These findings suggest that the chicken and turkey parvoviruses might have diverged from a common ancestor and have subsequently undergone host-specific adaptation.
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Specific pathogen free (SPF) White Leghorn chicken embryos and day-old chickens and day-old commercial broiler chickens were infected with a parvovirus (strain ABU) isolated from chickens with stunted growth. As a result, egg hatchability was significantly decreased and hatched chickens had enteritis and low vitality. Serious growth retardation, bad feathering and bone disorders were observed in infected broiler chickens. Similar signs were not seen in SPF White Leghorn chickens.
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Small viral particles of 19 to 24 nm in diameter with a buoyant density in CsCl of 1.43 g/ml were detected electron microscopically in samples taken from the gut of 10‐day‐old chickens suffering from a stunting syndrome. The viral particles are suggested to belong to the Parvoviridae and their possible role in the stunting syndrome is discussed. Resume De petites particules virales de 19 à 24 nm de diamètre, avec un gradient de densité en CsCl de 1, 43 g/ml ont été mises en évidence en microscopie électronique dans des échantillons d'intestin provenant de poulets âgés de 10 jours présentant le syndrome de dépérissement. Les particules virales semblent appartenir aux Parvoviridae et leur rôle possible dans l'étiologie du syndrome de dépérissement est discuté. Zusammenfassung Im Elektronenmikroskop wurden in Darmproben von zehn Tage alten Küken mit Stuntingsyndrom kleine Viruspartikel mit einem Durchmesser von 19 bis 24 nm und einer buoyanten Dichte in CsCl von 1, 43 g/ml nachgewiesen. Es wird vermutet, daβ die viralen Partikel zu den Parvoviridae gehören. Ihre mögliche Rolle beim Stuntingsyndrom wird diskutiert.
Article
Specific-pathogen-free White Leghorn chickens and commercial broilers were inoculated orally at 1 day of age with different intestinal preparations containing a chicken parvovirus, an entero-like virus associated with a reovirus from field materials, or the entero-like viruses and reovirus alone. Despite viral multiplication in inoculated birds, no clinical signs or growth retardation were observed in SPF and broiler chickens infected with the reo or parvoviruses. Abnormal faeces and reduction in weight gains were observed after infection with the field materials and the entero-like viruses. Some easily sedimentable particles could be involved with the entero-like virus in the aetiology of runting syndrome. Proventriculitis was present in chickens inoculated with one of the field materials and with the entero-like virus isolated from that material. Specific-pathogen-free White Leghorn chickens were as susceptible as commercial broiler chickens to weight gain depression after oral inoculation with crude homogenates at 1 day of age.
Article
Four flocks from one commercial market-turkey operation in Ohio were monitored for the presence of enteric viruses. Each flock was sampled at intervals from placement until at least 7 weeks of age; sampling was more frequent in the first 4 weeks of life. The earliest infections detected were astrovirus infections or combination infections of astrovirus and rotavirus-like virus (RVLV) or astrovirus and rotavirus. During the first 4 weeks of life, astrovirus was the most frequently detected virus, followed by RVLV, then rotavirus. These viruses were seldom detected beyond 4 weeks of age. In three of the four flocks, no viruses were detected in samples collected before 6 days of age; in one flock, however, rotavirus and astrovirus were identified from samples collected at 3 days of age. Experimental infection of specific-pathogen-free poults with astrovirus and RVLV produced enteric diseases in poults and demonstrated that astrovirus was shed into the intestinal tract before RVLV. Poults experimentally infected with astrovirus and RVLV displayed clinical signs of diarrhea and upon necropsy exhibited dilated ceca, frothy gaseous intestinal contents, and loss of intestinal tone.
Article
A viral enteric disease of young turkeys characterized by stunting of affected birds, diarrhea, and increased mortality is described. Eosinophilic intranuclear inclusion bodies were found in the absorptive epithelial cells of the ileum. Electron microscopy of formalin-fixed tissue revealed that the intestinal inclusions contained numerous loosely packed 15-to 20-nm hexagonal particles. The size, shape, and intranuclear location have been used to tentatively identify these particles as parvoviruses.
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A disease syndrome of broiler chickens is described. Affected birds exhibited poor pigmentation of the shanks, decreased weight gains, elevated feed conversions, poor feathering, enlargement of the proventriculus, and a decrease in the size of the gizzard. Reoviruses were isolated from affected chickens from several farms. Signs and lesions similar to those seen in chickens with the field syndrome were reproduced when these isolates were inoculated into day-old chicks with low levels of maternal antibody against viral arthritis. The pathogenicity of the viral isolates was variable. The incidence of lameness was much higher in those groups of chicks injected with these viruses than in the control groups.
Article
So-called runting stunting syndrome (RSS) afflicts chicks worldwide. The present study in Georgia chicks is the first report of unique histologic features of RSS pathology in chicks in the United States. Various combinations of avian nephritis virus, enterovirus-612, and reovirus were always isolated from chick small intestines. Ultrastructurally, only small round viruses were seen in small intestinal lesions. Although finding intralesional virus in small intestinal segments from chicks with signs and gross lesions consistent with RSS constitutes a reasonable criterion for making a diagnosis of this disease, chicks without intralesional viruses and with bacterial or protozoal enteritis may also be small and abnormally feathered. Because just what constitutes RSS remains a diagnostic dilemma, we recommend that the use of the imprecise acronym "RSS" be discontinued.
Article
Intestinal samples from turkey poults affected with poult enteritis and mortality syndrome (PEMS) were examined for viruses by immune electron microscopy and double-stranded RNA virus genome electropherotyping. Turkey coronavirus (TCV), avian rotaviruses, reovirus, and a yet undefined small round virus (SRV) were detected. The SRV and TCV were isolated and propagated in turkey embryos. Challenge of specific-pathogen-free turkey poults with SRV, TCV, or both resulted in mortality and clinical responses similar to those of natural PEMS. Our experiments indicate that SRV and TCV are possibly important agents in the etiology of PEMS and the combination of these infections might result in outbreaks with high mortality. The severity of clinical signs and mortality of PEMS are postulated to be partly related to the virus agents involved in individual outbreaks.
Article
Poult enteritis complex (PEC) is a general term that encompasses the infectious intestinal diseases of young turkeys. Some diseases, such as coronaviral enteritis and stunting syndrome, are relatively well characterised, while others, such as transmissible viral enteritis, poult growth depression and poult enteritis mortality syndrome, remain ill-defined. All forms of PEC are multifactorial, transmissible and infectious. Salient clinical features include stunting and poor feed utilisation that result from enteritis. In the more severe forms, runting, immune dysfunction and mortality are reported. Gross and microscopic lesions of enteritis are present in all forms but tend to be non-specific. Other lesions may be present, depending on the agents involved. The basic pathogenesis involves the following: a) alteration of the intestinal mucosa, generally by one or more viruses infecting enterocytes; b) inflammation; c) proliferation of secondary agents, usually bacteria. Non-infectious factors interplay with infectious agents to modulate the course and severity of disease. Diarrhoea is believed to be primarily osmotic because of maldigestion and malabsorption, but may also have a secretory component. Transmission is primarily faecal-oral. No public health significance is recognised or suspected. Prevention is based on eliminating the infectious agents from contaminated premises and preventing introduction into flocks. This is accomplished by an effective cleaning, disinfection and biosecurity programme. All-in/all-out production or separate brooding and finishing units are helpful. Control may require regional co-ordination among all companies producing turkeys, especially if the production is highly concentrated, and a quarantine programme for more severe forms of PEC. No vaccines or specific measures for controlling the organisms involved in PEC are available. Treatment is supportive for the viral component, while antibiotics, especially those with efficacy against Gram positive bacteria, may help to reduce the impact to bacterial infections. Evidence suggests that PEC occurs wherever turkeys are raised commercially, but this is not well documented and distribution of the various organisms that have been associated with PEC is largely unknown. The disease causes enormous economic loss, mostly from failure of the turkey to reach its genetic potential.
Article
Poult enteritis complex (PEC) is an economically important disease of young turkeys characterized by diarrhea, poor weight gain, and, in some cases, high mortality. Although PEC is considered to be a polymicrobial disease, numerous viruses, including turkey coronavirus (TCV), turkey astrovirus type 2 (TAstV-2), and avian reoviruses (ARVs), have been associated with PEC-like disease. Real-time reverse transcription-polymerase chain reaction (RRT-PCR), a highly sensitive and specific detection method for viral RNA, was developed in a multiplex format for the simultaneous detection of TAstV-2 and TCV and for the detection of two genetic types of ARV. Assay sensitivity was determined using in vitro transcribed RNA and varied by target between 150 gene copies for TAstV-2 alone and 2200 gene copies for TCV when multiplexed. Virus detection was evaluated with samples collected from poults inoculated at 1 day of age with each of the viruses. Cloacal swabs and intestinal samples were obtained at 1, 2, 3, 4, 6, 9, 14, 17, and 21 days after inoculation, processed, and tested for virus detection by RRT-PCR Cloacal swabs from TAstV-2- and TCV-infected poults were shown to have sensitivity for virus detection similar to that of intestinal samples when compared directly. ARV detection by RRT-PCR was compared with virus isolation and had similar sensitivity.
Article
Avian reoviruses that have been shown to be genetically distinct from chicken origin reoviruses were isolated from commercial turkey flocks in the Southeastern US and Texas that were experiencing enteritis. The pathogenesis of these turkey origin reoviruses (TRVs) was evaluated in commercial and specific pathogen free (SPF) turkey poults and SPF chickens. Mortality, clinical disease, gross lesions, microscopic lesions and body weights were observed. TRVs replicated poorly and did not cause disease in chickens. Clinical disease induced by the TRV isolates, characterized by diarrhoea and depression, was mild in both SPF and commercial origin poults. Several TRV isolates caused moderate to severe bursal atrophy in poults. Additionally, each of the TRV isolates caused significant body weight decreases in SPF and/or commercial poults as compared with sham inoculates. Molecular characterization of the isolates revealed that the TRVs and chicken origin reoviruses had identical electropherotype profiles.
Article
Based on previous reports characterizing the turkey-origin avian reovirus (TRV) sigmaB (sigma2) major outer capsid protein gene, the TRVs may represent a new group within the fusogenic orthoreoviruses. However, no sequence data from other TRV genes or genome segments has been reported. The sigmaC protein encoded by the avian reovirus S1 genome segment is the cell attachment protein and a major antigenic determinant for avian reovirus. The chicken reovirus S1 genome segment is well characterized and is well conserved in viruses from that species. This report details the amplification, cloning and sequencing of the entire S1 genome segment from two and the entire coding sequences of the sigmaC, p10 and p17 genes from an additional five TRVs. Sequence analysis reveals that of the three proteins encoded by the TRV S1 genome segment, sigmaC shares at most 57% amino acid identity with sigmaC from the chicken reovirus reference strain S1133, while the most similar p10 and p17 proteins share 72% and 61% identity, respectively, with the corresponding S1133 proteins. The most closely related mammalian reovirus, the fusogenic Nelson Bay reovirus, encodes a sigmaC protein that shares from 25% to 28% amino acid identity with the TRV sigmaC proteins. This report supports the earlier suggestion that the TRVs are a separate virus species within the Orthoreovirus genus, and may provide some insight into TRV host specificity and pathogenesis.
Article
The pathogenesis of 4 isolates of turkey-origin reovirus (NC/SEP-R44/03, NC/98, TX/98, and NC/85) and 1 chicken-origin reovirus (1733) was examined by infecting specific pathogen free (SPF) poults. These turkey-origin reovirus (TRV) isolates were collected from turkey flocks experiencing poult enteritis and are genetically distinct from previously reported avian reoviruses. Microscopic examination of the tissues collected from the TRV-infected poults revealed different degrees of bursal atrophy characterized by lymphoid depletion and increased fibroplasia between the bursal follicles. To understand the relationship between virus spread and replication, and the induction of lesions, immunohistochemical staining (IHC) for viral antigen, in situ hybridization (ISH) for the detection of viral RNA, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay for the detection of apoptosis in affected tissues was performed. Both IHC and ISH revealed viral antigen and RNA in the surface epithelial cells of the bursa, in macrophages in the interstitium of the bursa and, to lesser degree, in splenic red pulp macrophages and intestinal epithelial cells. Increased apoptosis of bursal lymphocytes and macrophages was observed at 2 and 5 days postinoculation. No lesions were found in tissues from poults inoculated with the virulent chicken-origin strain, however viral antigen was detected in the bursa and the intestine. Although all TRVs studied displayed similar tissue tropism, there were substantial differences in the severity of the lesions produced. Poults inoculated with NC/SEP-R44/03 or NC/98 had moderate to severe bursal atrophy, whereas poults inoculated with TX/98 or NC/85 presented a mild to moderate bursal lymphoid depletion. The lymphoid depletion observed in the bursa appears to be the effect of an indirectly induced apoptosis and would most likely result in immune dysfunction in poults infected with TRV.
Article
Recent studies have revealed the presence ofastroviruses and rotavirus in numerous poorly performing and healthy chicken and turkey flocks in the United States. The phylogenetic analysis of the sequence data produced during these studies has identified four groups of avian astroviruses circulating in the United States: turkey astrovirus types 1 and 2 (TAstV-1 and TAstV-2), avian nephritis virus (ANV), and a chicken-origin astrovirus (CAstV). As the molecular epidemiology of poultry enteric disease is poorly understood, the development of updated diagnostic assays is crucial to the continued surveillance and management of enteric disease in affected as well as healthy flocks. This report details the development of a multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) assay specific for astroviruses and avian rotavirus in turkey-origin and chicken-origin samples. The assay consists of two multiplex tests, one for turkey-origin samples and one for chicken-origin samples. The turkey sample test differentially identifies TAstV-1, TAstV-2, ANV, and avian rotavirus. The test for chicken-origin samples differentially identifies CAstV, ANV, and avian rotavirus. Assay sensitivity varied by target sequence between approximately 10 copies for avian rotavirus alone and approximately 2 x 10(6) copies for TAstV-2 in the presence of a heterologous competitor RNA sequence. Each test was shown to be specific for the intended target by testing for cross-reaction with other common avian enteric viruses. The specificity was further shown by testing 109 chicken specimens and 32 turkey specimens from commercial flocks with the appropriate test and sequencing the RT-PCR amplicons to confirm amplification of the correct target.
Article
A longitudinal survey to detect enteric viruses in intestinal contents collected from turkeys in eight commercial operations and one research facility was performed using molecular detection methods. Intestinal contents were collected from turkeys prior to placement, with each flock resampled at 2, 4, 6, 8, 10, and 12 wk of age. The samples were screened for astrovirus, rotavirus, reovirus, and turkey coronavirus (TCoV) by a reverse transcriptase and polymerase chain reaction (RT-PCR), and for groups 1 and 2 adenovirus by PCR. Rotavirus was the only virus detected prior to placement (7 of 16 samples examined). All of the commercial flocks were positive for rotavirus and astrovirus from 2 until 6 wk of age, and most were intermittently positive until 12 wk of age, when the birds were processed. Of the 96 samples collected from birds on the farms, 89.5% were positive for astrovirus, and 67.7% were positive for rotavirus. All flocks were negative for TCoV, reovirus, and group 1 adenovirus at all time points, and positive for group 2 adenovirus (hemorrhagic enteritis virus) at 6 wk of age. All the flocks monitored were considered healthy or normal by field personnel. Turkeys placed on research facilities that had been empty for months and thoroughly cleaned had higher body weights and lower feed conversion rates at 5 wk of age when compared to turkeys placed on commercial farms. Intestinal samples collected at 1, 2, and 3 wk of age from these turkeys were free of enteric viruses. This report demonstrates that astroviruses and rotaviruses may be present within a turkey flock through the life of the flock. Comparison of infected birds with one group of turkeys that were negative for enteric viruses by the methods used here suggests that astrovirus and/or rotavirus may affect production. The full impact on flock performance needs to be further determined.
Article
The pathogenicity of three different type 2 turkey astroviruses (TAstV-2) was studied in specific pathogen free turkeys. These viruses differ based on sequence analysis of the capsid gene. Poults were inoculated at 2 days of age and examined during 14 days for clinical signs and virus shedding. All inoculated poults presented signs of enteric disease including diarrhoea and growth depression. Virus presence and shedding was detected by real-time reverse transcriptase-polymerase chain reaction from intestinal contents and cloacal swabs collected at 3, 7 and 14 days post-inoculation. Viraemia was also confirmed by this method. Common lesions observed at necropsy were dehydration; distended intestines filled with watery contents and undigested feed, and dilated caeca with foamy contents. Microscopic lesions present in the intestines consisted of mild crypt hyperplasia, villous atrophy and lymphocytic infiltration, and were most common in the jejunum. Presence of the viruses was demonstrated by immunohistochemistry and by in situ hybridization in both villi and crypt enterocytes in the jejunum and, less frequently, the duodenum, ileum and caeca. Mild lesions consisting mainly of lymphocytic infiltration were also observed in other organs including the pancreas, liver, spleen and kidneys. Mild to moderate bursal atrophy occurred in all TAstV-2-infected poults examined; however, no specific viral staining was observed in this organ or any other tissues examined apart from the intestines. In conclusion, TAstV-2 viruses with variant capsids produce a similar enteric disease in young turkeys and may also affect the immune system of the birds by causing bursal lymphoid depletion.
Article
Human bocavirus (HBoV) is a newly identified human parvovirus for which seroepidemiology and antigenic properties remain undefined. The HBoV VP2 gene, expressed from a baculovirus vector, produced virus-like particles (VLPs), which were used to raise rabbit anti-HBoV antisera and to develop an enzyme-linked immunosorbent assay (ELISA). The VLP-based ELISA was used to screen for HBoV-specific immunoglobulin G antibodies in a convenience sample of 270 serum specimens, mostly from children, obtained at Yale-New Haven Hospital; 208 specimens were also screened for erythrovirus B19-specific antibodies by a B19 VLP-based ELISA. Immunofluorescence and ELISA showed that human parvoviruses HBoV and B19 are antigenically distinct. By the HBoV VLP-based ELISA, 91.8% and 63.6% of serum specimens from infants in the first and second months of life, respectively, were found to be seropositive, as were 45.4% from 3-month-old infants and 25.0% from 4-month-old infants. The percentages of HBoV-seropositive children increased to 40.7%-60.0% for children 5-47 months of age and to >85% for individuals >or=48 months old. However, the overall percentage of B19-seropositive individuals was <40.5% for all age groups screened. HBoV infection is common during childhood, but a minority of children and young adults screened have evidence of B19 infection.
Article
Poult enteritis mortality syndrome (PEMS) of turkeys and runting-stunting syndrome (RSS) of chickens are significant viral enteric diseases of poultry. Although a number of different viruses, including avian reoviruses, rotaviruses, astroviruses and coronaviruses, have been isolated from the intestinal contents of birds in affected poultry flocks, their role in PEMS and RSS is not yet understood. Here, we report the application of a molecular screening method to detection of novel viruses in intestinal samples of chickens and turkeys exhibiting characteristic signs of enteric disease. The technique is based on random amplification of particle-associated nucleic acids in clinical samples. Using this method we successfully identified parvovirus DNA sequences in intestinal homogenates of affected birds. This is the first time partial genomic sequences of autonomously replicating chicken and turkey parvoviruses have been described. Sequence analysis of the left end of the genome, including the complete non-structural gene, demonstrated that the chicken and turkey parvoviruses were closely related to each other and were representative of a novel member of the Parvovirus family. These parvoviruses may play a significant role in the aetiology of PEMS and RSS.