Experimental Parasitology (Exp Parasitol )

Publisher: Elsevier


Experimental Parasitology emphasizes modern approaches to parasitology, including molecular biology and immunology. The journal features original research papers on the physiological, metabolic, immunologic, biochemical, nutritional, and chemotherapeutic aspects of parasites and hostñparasite relationships.

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    Experimental Parasitology website
  • Other titles
    Experimental parasitology (Online), Experimental parasitology, EP
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    Document, Periodical, Internet resource
  • Document type
    Internet Resource, Computer File, Journal / Magazine / Newspaper

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Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Leishmania amazonensis is a protozoan parasite that induces mucocutaneous and diffuse cutaneous lesions upon infection. An important component in treatment failure is the emergence of drug-resistant parasites. It is necessary to clarify the mechanism of resistance that occurs in these parasites to develop effective drugs for leishmaniasis treatment. Promastigote forms of Leishmania amazonensis were selected by gradually increasing concentrations of vinblastine and were maintained under continuous drug pressure (resistant cells). Vinblastine-resistant L. amazonensis proliferated similarly to control parasites. However, resistant cells showed changes in the cell shape, irregular flagella and a decrease in rhodamine 123 accumulation, which are factors associated with the development of resistance, suggesting the MDR phenotype. The Mg-dependent-ecto-ATPase, an enzyme located on cell surface of Leishmania parasites, is involved in the acquisition of purine and participates in the adhesion and infectivity process. We compared control and resistant L. amazonensis ecto-enzymatic activities. The control and resistant Leishmania ecto-ATPase activities were 16.0 ± 1.5 nmol Pi × h(-1) × 10(-7) cells and 40.0 ± 4.4 nmol Pi × h(-1) × 10(-7)cells, respectively. Interestingly, the activity of other ecto-enzymes present on the L. amazonensis cell surface, the ecto-5' and 3'-nucleotidases and ecto-phosphatase, did not increase. The level of ecto-ATPase modulation is related to the degree of resistance of the cell. Cells resistant to 10 μM and 60 μM of vinblastine have ecto-ATPase activities of 22.7 ± 0.4 nmol Pi × h(-1) × 10(-7) cells and 33.8 ± 0.8 nmol Pi × h(-1) × 10(-7)cells, respectively. In vivo experiments showed that both lesion size and parasite burden in mice infected with resistant parasites are greater than those of L. amazonensis control cells. Furthermore, our data established a relationship between the increase in ecto-ATPase activity and greater infectivity and severity of the disease caused by vinblastine-resistant L. amazonensis promastigotes. Taken together, these data suggest that ecto-enzymes could be potential therapeutic targets in the struggle against the spread of leishmaniasis, a neglected world-wide public health problem.
    Experimental Parasitology 08/2014;
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    ABSTRACT: Cryptosporidiosis is prevalent in domesticated, caged, and wild birds. Cryptosporidium baileyi, an ascendant species of avian Cryptosporidium, is an important pathogen. It causes respiratory disease in chickens, especially chickens younger than 50 days. In this study, SEM, histological, semi-quantitative PCR, and nested PCR techniques were used to explore the impact of different inoculation routes on sites of C. baileyi infection in chickens. Results showed that inoculation with sporozoites or oocysts via the rectum was an effective means of causing infection. This may provide an important reference for the development of the transfection system of C. baileyi in chickens. Numerous endogenous stages of C. baileyi were observed in the bursas of Fabricius (BF) and cloacas of chickens inoculated with sporozoites or oocysts via the rectum, but no parasite was seen in the tracheas of any of these chickens. In chickens infected with oocysts via the crop, the number of parasites in the BF was approximately 23-fold more than in the trachea. All blood samples collected after inoculation were negative for C. baileyi. These data show that C. baileyi was not transferred by blood circulation between the BF and respiratory tract. Different routes of inoculation were here found to distinctly affect sites of parasitism in chickens. These findings may facilitate further understanding of the biology of C. baileyi and efforts to control avian cryptosporidiosis.
    Experimental Parasitology 08/2014;
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    ABSTRACT: We developed a protocol to inactivate Toxoplasma gondii (T. gondii) tachyzoites employing 1 minute of ultraviolet (UV) exposure. We show that this treatment completely inhibited parasite replication and cyst formation in vitro and in vivo but did not affect the induction of a robust IgG response in mice. We propose that our protocol can be used to study the contribution of the humoral immune response to rodent behavioral alterations following T. gondii infection.
    Experimental Parasitology 08/2014;
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    ABSTRACT: Trypanosoma rangeli is a protozoan parasite of insects and mammals that is challenged by the constant action of reactive oxygen species, generated either by its own metabolism or through the host immune response. The aim of this work was to investigate whether T. rangeli is able to modify the redox state of its insect vector, Rhodnius prolixus, through the modulation of such antioxidant enzymes as superoxide dismutase (SOD), catalase, and GPx present in the midgut of the insect. We verified that in R. prolixus fed with blood infected with T. rangeli there is an increase in SOD activity in the anterior and posterior midguts. However, the activities of enzymes related to hydrogen peroxide and hydroperoxides metabolism, such as catalase and GPx, were decreased in relation to the insect control group, which was only fed blood. These changes in the redox state of the vector led to an increase in lipid peroxidation and thiol oxidation levels in the anterior and posterior midgut tissues. We also verified that the addition of 1 mM GSH in the blood meal of the infected insects increased the proliferation of these parasites by 50%. These results suggest that there is an increase in oxidative stress in the insect gut during T. rangeli infection, and this condition could contribute to the control of the proliferation of these parasites.
    Experimental Parasitology 08/2014;
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    ABSTRACT: Here we reported our investigation, as part of our drug repositioning effort, on anti-Toxoplasma properties of newly synthesized quinoline compounds. A collection of 4-aminoquinoline and 4-piperazinylquinoline analogs have recently been synthesized for use in cancer chemotherapy. Some analogs were able to outperform chloroquine, a quinoline derivative drug which is commonly used in the treatment of malaria and other parasitic infections. Herein 58 compounds containing one or two quinoline rings were examined for their effectiveness as potential anti-Toxoplasma compounds. Of these 58 compounds, 32 were efficient at inhibiting Toxoplasma growth (IC50 < 100 μM). Five compounds with single and simple quinoline rings exhibited similar cLogP values of ∼2 and IC50 values between 5 - 6 μM, with one exception of 8-hydroxyquinoline whose IC50 value was 213 nM. The addition of one hydroxyl group at position 8 caused a 40-fold increase in the inhibitory effect of quinoline. A significant improvement in anti-Toxoplasma effect among quinoline derivatives was detected in B11, B12, B23, and B24, whose structures carry two quinoline rings, and their resultant cLogP values are ⩾7. Among these compounds, B23 was the most effective compound with IC50 value of 425 ± 35 nM, and TI value of 4.9. It was also noted that compounds with at least one quinoline ring, displaying anti-Toxoplasma effects were capable of causing the disappearance of the apicoplast, a plastid-like organelle. When treated with quinoline, 8-hydroxyquinoline or B23, 40 - 45% of the parasites lost their apicoplasts. Our findings recapitulate the properties of quinoline derivatives in diminishing apicoplast. This could aid further investigations of anti-parasitic treatments specific to Apicomplexan. More importantly, B12 and B23 which harbor superior anti-cancer properties than chloroquine, have effective anti-Toxoplasma activity. These compounds therefore have significant potential for future development of chemotherapeutic agents for patients suffering from breast cancers and parasitic infection.
    Experimental Parasitology 08/2014;
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    ABSTRACT: Leishmaniasis, a neglected tropical disease (NTD) causes major health problems in the tropical and subtropical world. Most of the antileishmanial modern therapies with different formulations of pentavalent antimonials, Miltefosine, Amphotericin B etc are not satisfactory in recent times due to high toxicity to the host and present rising strain resistance issues. So there is an urgent need to develop new, safe and cost-effective drugs against leishmaniasis. In this regard, bioactive phytocomponents may lead to the discovery of new medicines with appropriate efficiency. The prominent roles played by Leishmania proteases in the virulence of this parasite make them very promising targets for the development of current therapeutics of leishmaniasis. As part of a search for novel drugs, we have evaluated in vitro anti-leishmanial activity of serine potease inhibitor rich fraction (PTEx) obtained from potato tuber. The extract (PTEx) was prepared by sodium bisulphite fractionation and inhibitors were identified by reverse zymography. Inhibition study of PTEx in gelatin-zymogram and spectrophotometric assay using BApNA and BTpNA as substrate reveal its strong inhibitory activity against trypsin as well as serine proteases present in cell lysate of Leishmania donovani infective strain. The in vitro MTT based colorimetric assay as well as ex vivo L. donovani infected macrophages showed reduced parasite viability and intracellular parasite load with IC50=312.5 ± 0.1μg/ml and IC50 82.3 ± 0.2 μg/ml of PTEx respectively in a concentration dependent manner. This anti-leishmanial effect was also preceded by PTEx induced acute formation of ROS and prolonged NO generation. The PTEx has no significant cytotoxic effect on host macrophages. So taken together, these findings indicate that PTEx has promising leishmanicidal effect and thus this study provides a new perspective of natural serine protease inhibitor from potato tuber on the development of new drug against leishmaniasis.
    Experimental Parasitology 08/2014;
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    ABSTRACT: Aminopeptidase H11 present in the surface of intestine microvilli in Haemonchus contortus was identified as the most effective antigen candidate. However, its recombinant forms produced in E. coli, insect cells and yeast could not provide promising protection against H. contortus challenge, probably due to the inappropriate glycosylation and/or conformational folding. Herein, partial H11 containing the potential zinc-binding domain and two predicted glycosylation sites (nt 1 bp-1710 bp, Trans-HPS) was subcloned downstream of 5' flanking region of Caenorhabditis elegans cpr-1 gene in pPD95.77 vector, with the deletion of GFP gene. The recombinant was expressed in C. elegans and verified by blotting with anti-H11 and anti-Trans-HPS rabbit polyclonal antibodies and anti-His monoclonal antibody. Stably inherited Trans-HPS in worm descendants was achieved by integration using UV irradiation. Immunization with the crude Trans-HPS extracted from transgenic worms resulted in 37.71% reduction in faecal egg counts (FEC) (P<0.05) and 24.91% reduction in worm burden, but an upward curve with moderate rate of daily FEC in goats. These results suggested an apparent delay against H. contortus egg-laying in goats, which differed from that with bacteria-origin form of partial H11 (nt 670 bp-1710 bp, HPS) (26.04% reduction in FEC and 18.46% reduction in worm burden). These findings indicate the feasibility of sufficient C. elegans-expressed H11 for the immunological research and vaccine development.
    Experimental Parasitology 08/2014;
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    ABSTRACT: Automated extraction of DNA for testing of laboratory samples is an attractive alternative to labour-intensive manual methods when higher throughput is required. However, it is important to maintain the maximum detection sensitivity possible to reduce the occurrence of type II errors (false negatives; failure to detect the target when it is present), especially in the biomedical field, where PCR is used for diagnosis. We used blood infected with known concentrations of Trypanosoma copemani to test the impact of analysis techniques on trypanosome detection sensitivity by PCR. We compared combinations of a manual and an automated DNA extraction method and two different PCR primer sets to investigate the impact of each on detection levels. Both extraction techniques and specificity of primer sets had a significant impact on detection sensitivity. Samples extracted using the same DNA extraction technique performed substantially differently for each of the separate primer sets. Type I errors (false positives; detection of the target when it is not present), produced by contaminants, were avoided with both extraction methods. This study highlights the importance of testing laboratory techniques with known samples to optimise accuracy of test results.
    Experimental Parasitology 08/2014;
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    ABSTRACT: Multidrug resistant Plasmodium falciparum is the major health problem in the tropics. Discovery and development of new antimalarial drugs with novel modes of action is urgently required. The aim of the present study was to investigate antimalarial activities of Garcinia mangostana Linn. crude ethanolic extract including its bioactive compounds as well as the metabolic footprinting of P. falciparum following exposure to G. mangostana Linn. extract. The median (range) IC50 (concentration that inhibits parasite growth by 50%) values of ethanolic extract of G. mangostana Linn., α-mangostin, β-mangostin, gartanin, 9-hydroxycarbaxathone, artesunate, and mefloquine for 3D7 vs K1 P. falciparum clones were 12.6 (10.5-13.2) vs 4.5 (3.5-6.3) μg/ml, 7.3 (7.1-8.5) vs 5.0 (3.7-5.9) μg/ml, 47.3 (46.8-54.0) vs 35.0 (30.0-43.7) μg/ml, 9.2 (8.1-11.9) vs 6.8 (6.2-9.1) μg/ml, 0.6 (0.4-0.8) vs 0.5 (0.4-0.7) μg/ml, 0.4 (0.2-1.2) vs 0.7 (0.4-1.0) ng/ml, and 5.0 (4.2-5.0) vs 2.7 (2.5-4.6) ng/ml, respectively. The action of G. mangostana Linn. started at 12 hours of exposure, suggesting that the stage of its action is trophozoite. The 12-hour exposure time was used as a suitable exposure time for further analysis of P. falciparum footprinting. G. mangostana Linn. extract was found to target several metabolic pathways particularly glucose and TCA metabolisms. The malate was not detected in culture medium of the exposed parasite, which may indirectly imply that the action of G. mangostana Linn. is through interruption of TCA metabolism.
    Experimental Parasitology 08/2014;
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    ABSTRACT: Schistosomiasis continues to be a serious helminthic disease that is widespread in many regions in the world. Disease management relies mainly on early treatment with praziquantel, nevertheless, re-infection rates can still be high. An effective vaccine against Schistosoma mansoni is still lacking; a situation which hinders the efforts to eradicate the disease worldwide. Most investigators test S. mansoni antigens individually, rather than in combination, in their vaccine trials. A single-antigen vaccine is likely to elicit less protection against schistosomiasis than a multi-antigen vaccine. In the current study, we have selected two promising S. mansoni antigens, Sm14 and Sm29, and investigated their combination as a potential vaccine. Recombinant Sm14 and a truncated form of Sm29, designated TrSm29, were successfully expressed in E. coli. The two antigens were purified using affinity chromatography and administered to Swiss albino mice individually and in combination. Significant protection against S. mansoni infection was observed in mice immunized with the Sm14/TrSm29 combination in the presence/absence of the immunoadjuvant poly (I:C). The poly (I:C)-adjuvanted combination resulted in 40.3%, 68.2%, and 57.9% reduction in adult worm burden, liver egg burden and intestinal eggs, respectively. Granuloma size and count were also reduced besides improvement of the histopathological picture of livers of immunized mice. This study demonstrates the importance of using multi-antigen vaccines as an effective and simple approach to fulfill enhanced protection against schistosomiasis.
    Experimental Parasitology 08/2014;
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    ABSTRACT: The glycolytic enzyme phosphoglycerate kinase (PGK) is present in Trypanosoma cruzi as three isoenzymes, two of them located inside glycosomes (PGKA and PGKC) and another one in the cytosol (PGKB). The three isoenzymes are expressed at all stages of the life cycle of the parasite. A heterologous expression system for PGKA (rPGKA) was developed and the substrate affinities of the natural and recombinant PGKA isoenzyme were determined. Km values measured for 3-phosphoglycerate (3PGA) were 174 and 850 μM, and for ATP 217 and 236 μM, for the natural and recombinant enzyme, respectively. No significant differences were found between the two forms of the enzyme. The rPGKA was inhibited by Suramin with Ki values of 10.08 μM and 12.11 μM for ATP and 3PGA, respectively, and the natural enzyme was inhibited at similar values. A site-directed mutant was created in which the 80 amino acids PGKA sequence, present as a distinctive insertion in the N-terminal domain, was deleted. This internally truncated PGKA showed the same Km values and specific activity as the full-length rPGKA. The natural PGKC isoenzyme was purified from epimastigotes and separated from PGKA through molecular exclusion chromatography and its kinetic characteristics were determined. The Km value obtained for 3PGA was 192 μM, and 10 μM for ATP. Contrary to PGKA, the activity of PGKC is tightly regulated by ATP (substrate inhibition) with a Ki of 270 μM, suggesting a role for this isoenzyme in regulating metabolic fluxes inside the glycosomes.
    Experimental Parasitology 08/2014; 143:39-47.
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    ABSTRACT: Free-living amoebae have been found in soil, air and a variety of aquatic environments, but few studies have been conducted on industrial wastewater and none on wastewater from the textile industry. The aim of this study was to determine the presence and distribution of free-living amoebae in a biological treatment system that treats textile industrial wastewater. Samples were taken from input, aeration tank, sedimentation tank and output. Samples were centrifuged at 1200 g for 15 minutes, the sediment was seeded on non-nutritive agar with Enterobacter aerogenes (NNE) and the plates were incubated at 30 and 37°C. Free-living amoebae were present in all stages of the treatment system. The highest number of amoebic isolates was found in the aeration tank and no seasonal distribution was observed during the year. A total of 14 amoeba genera were isolated: Acanthamoeba, Echinamoeba, Korotnevella, Mayorella, Naegleria, Platyamoeba, Saccamoeba, Stachyamoeba, Thecamoeba, Vahlkampfia, Vannella, Vermamoeba, Vexillifera and Willaertia. The most frequently found amoebae were Acanthamoeba and Vermamoeba which were found in all treatment system stages. The constant presence and diversity of free-living amoebae in the treatment system were important findings due to the characteristics of the wastewater from the textile plant in terms of the residue content from colorants, fixers, carriers, surfactants, etc., used in fabric dyeing and finishing processes. The factors that determined the presence and distribution of amoebae in the activated sludge system were their capacity to form cysts, which allowed them to resist adverse conditions; food availability; an average temperature of 27 to 33°C; dissolved oxygen in average concentrations above 2 mg/L, and pH in a range of 5.9 to 7.1.
    Experimental Parasitology 07/2014;
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    ABSTRACT: In a previous study we have shown that the in vitro invasion rate (IR) and tachyzoite yield (TY) are associated with the virulence phenotypes of Neospora caninum isolates of bovine origin. In addition, we recently observed marked differences in virulence when canine isolates were compared in a pregnant BALB/c mouse model. In this study, we investigated whether invasion and proliferation capacities could be used as virulence-related N. caninum phenotypic traits. Of the isolates compared in mice, four canine isolates obtained from oocysts (Nc-Ger2, Nc-Ger3, Nc-Ger-6, Nc-6 Arg) had shown a low-moderate virulence, and two further isolates obtained from dogs with neurological signs (Nc-Bahia, Nc-Liv) were highly virulent. The IR for each isolate was determined by a plaque assay and the counting of immunofluorescence-labeled parasitophorous vacuoles at 3 days post-inoculation (p.i.). The TY was determined by the quantification of tachyzoites at 56 h p.i. by real-time PCR. Most of the canine isolates showed similar IR values under controlled invasion conditions for 4 h and 72 h p.i., indicating a limited time period for invasion similar to that observed for bovine isolates. The Nc-Ger3, Nc-Bahia, and Nc-Liv isolates showed a significantly higher IR and TY than the Nc-Ger2 and Nc-Ger6 isolates (P<0.0001). A correlation was found between the IRs and TY (ρ>0.885, P<0.033), as well as between the TY and both dam morbidity (ρ=0.8452, P<0.033) and pup mortality (ρ>0.8117, P<0.058) in mice. These results demonstrate the importance both the invasive and proliferative capacities have on the virulence of canine N. caninum isolates.
    Experimental Parasitology 07/2014;

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