bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diethylcarbamazine (DEC): immunopharmacological interactions of an anti-filarial drug
Authors: Maizels R. M. , Denham D. A. 
Published: June 2009

SUMMARYAnti-parasitic drugs may achieve their therapeutic effect either by direct activity against the pathogenic organism, or by altering host factors which lead to parasite killing. In this review, we discuss the evidence for an indirect mode of action for one major anti-filarial drug, diethylcarbamazine (DEC). The interpretation most consistent with existing data is that DEC alters arachidonic acid metabolism in microfilariae and in host endothelial cells. These changes may result in vasoconstriction and amplified endothelial adhesion leading to immobilization of microfilarial parasites, enhanced adherence and cytotoxic activity by host platelets and granulocytes. These events would represent activation of the innate, non-specific immune system, independent of the adaptive, antigen-specific, immune response. This model explains the paradox between rapid clearancein vivoand the lack of anin vitroeffect, as well as the efficacy of DEC in non-immune animals.
Interactions between immunity and chemotherapy in the treatment of the trypanosomiases and leishmaniases
Authors: Berger B. J. , Fairlamb A. H. 
Published: June 2009

SUMMARYThe immune status of a host infected withTrypanosomaspp. orLeishmaniaspp. can play an important role in successful chemotherapy. In animal models, treatment of African trypanosomiasis with difluoromethylornithine or melarsoprol requires an appropriate antibody-mediated immune response. An intact immune system is also necessary for rapid clearance of trypanosomes from the bloodstream following treatment with suramin or quinapyramine. Similarly, an efficient cell-mediated immune response is required for maximal efficacy of pentavalent antimonials in the treatment of leishmaniasis. However, the potential relationship between parasite-induced or acquired immunosuppression and effective chemotherapy has been poorly studied. Macrophages which have been activated by bacterial cell wall components or gamma-interferon are known to display increased activity againstLeishmania donovaniorTrypanosoma cruzi. In experimental and clinical visceral leishmaniasis, use of macrophage activators together with pentavalent antimonials has lowered the dose of antimony required to cure the infection.
Maintenance of a microparasite infecting several host species: rabies in the Serengeti
Authors: Cleaveland S. , Dye C. 
Published: June 2009

SUMMARYWhether and how microparasites such as rabies persist in their host populations are among the fundamental questions of infectious disease epidemiology. Rabies is a fatal disease of all mammalian species, but not all mammalian species can maintain the infection as reservoirs. The approach to control depends on which of the affected species do act as reservoirs. Bringing together old and new data, we examine here the role of wild and domestic animals in maintaining rabies in the Serengeti region of Tanzania, presenting our findings in two parts. In Part I, we argue that domestic dogs are the likely reservoirs because: (1) rabies has been continuously present in the dog population since its (re)introduction in 1977, whilst (2) wildlife cases have been very rare over this period, despite intensive study of Serengeti carnivores; (3) outbreaks of rabies in wild canids (jackals) elsewhere in Africa (Zimbabwe) have followed, rather than preceded, outbreaks in the dog population; (4) all viruses isolated from wild carnivores in the Serengeti ecosystem (including the Kenyan Masai Mara) are antigenically and genetically indistinguishable from the typical domestic dog Strain; (5) dog rabies control in the Serengeti between 1958–77 apparently eliminated the disease from both dogs and wildlife. Having identified dogs as reservoirs, Part II explores some possible mechanisms of maintenance in dog populations. In theory, infection is more likely to be maintained at higher dog densities, and we provide evidence that rabies is maintained in one district with a dog density > 5/km2, but not in two other districts with densities < 1/km2. Because 5 dogs/km2is much lower than the expected density required for persistence, we go on to investigate the role of atypical infections, showing: (1) from serology, that a substantial proportion of healthy dogs in the Serengeti have detectable serum levels of rabies-specific antibody; (2) from mathematical models that, whilst we cannot be sure what seropositivity means, persistence in low-density dog populations is more likely if seropositives are infectious carriers, rather than slow-incubators or immunes.
Modelling patterns of parasite aggregation in natural populations: trichostrongylid nematode–ruminant interactions as a case study
Authors: Grenfell B. T. , Wilson K. , Isham V. S. , Boyd H. E. G. , Dietz K. 
Published: June 2009

SUMMARYThe characteristically aggregated frequency distribution of macroparasites in their hosts is a key feature of host–parasite population biology. We begin with a brief review of the theoretical literature concerning parasite aggregation. Though this work has illustrated much about both the sources and impact of parasite aggregation, there is still no definitive analysis of both these aspects. We then go on to illustrate the use of one approach to this problem – the construction of Moment Closure Equations (MCEs), which can be used to represent both the mean and second moments (variances and covariances) of the distribution of different parasite stages and phenomenological measures of host immunity. We apply these models to one of the best documented interactions involving free-living animal hosts – the interaction between trichostrongylid nematodes and ruminants. The analysis compares patterns of variability in experimental infections ofTeladorsagia circumcinctain sheep with the equivalent wildlife situation – the epidemiology ofT. circumcinctain a feral population of Soay sheep on St Kilda, Outer Hebrides. We focus on the relationship between mean parasite load and aggregation (inversely measured by the negative binomial parameter,k) for cohorts of hosts. The analysis and empirical data indicate thatktracks the increase and subsequent decline in the mean burden with host age. We discuss this result in terms of the degree of heterogeneity in the impact of host immunity or parasite-induced mortality required to shorten the tail of the parasite distribution (and therefore increasek) in older animals. The model is also used to analyse the relationship between estimated worm and egg counts (since only the latter are often available for wildlife hosts). Finally, we use these results to review directions for future work on the nature and impact of parasite aggregation.
Infrapopulation dynamics of Gyrdicotylus gallieni (Monogenea: Gyrodactylidae)
Authors: Jackson J. A. , Tinsley R. C. 
Published: June 2009

SUMMARYGyrdicotylus gallieni is a viviparous gyrodactylid monogenean that infects the buccal cavity and pharynx oi Xenopus laevis laevis. Offspring directly recolonize the same host as their parent and transmission is carried out exclusively by adult worms which are capable of leech-like stepping locomotion. The infrapopulation dynamics (at 20 °C) of this species were studied by experimental exposure to single worms of previously uninfected hosts (which were dissected at various time intervals post-infection). Infrapopulations increased exponentially until 50 days post-infection (p.i.), during which time the intrinsic rate of increase was estimated by regression as 0·065/parasite/day. After this, infrapopulation sizes showed greater variability, with established infections becoming extinct 2–5 months p.i.: elimination was probably due to someform of host reaction, as parasite lineages were maintained for up to 10 months by transfers to successive uninfected hosts.The development of infrapopulations is similar to that reported for other viviparous gyrodactylids parasitic on the bodysurface of teleosts. However, the intrinsic rate of increase was comparatively slow in G. gallieni and the duration of infection in isolated hosts prolonged. Slow-growing infrapopulations may elicit a host response more slowly and extend the period during which dispersal to a new host or host population can occur. This might be important in G. gallieni for which the internal site of infection could limit the transmission rate, as worm migration from the oral cavity or accidental detachment and expulsion is necessary for host-host transfer to occur. Exposure of wild caught X. l. laevis of unknown infectionhistory to 1 (n = 33) or 10 (n = 10) worms produced only 2 established infrapopulations (in both cases hosts initially infected by single worms), compared with establishment of over 60% in naive hosts infected with single worms: this suggests that host resistance may be an important factor in the population dynamics of G. gallieni.
Magnesium deficiency protects againstBabesia hylomysciand mice become resistant to rechallenge with the parasite regardless of diet fed
Authors: Maurois P. , Delcourt P.H. , Gueux E. , Rayssiguier Y. 
Published: June 2009

SUMMARYMice were fed diets containing 960 mg (control), 100 mg (moderately Mg deficient) and 30 mg (severely Mg deficient) of Mg/kg. After 20 days, mice were inoculated withBabesia hylomysci(from Dr Wery, Anvers, Belgium). Significant increases in RBC Mg levels were observed following infection. All the control and moderately deficient mice died from infection, whereas the severely Mg-deficient diet protected mice against infection, as shown by a decrease in parasitaemia and mortality. The decrease in RBC Mg, modifications in membrane properties and increased oxidant stress are possible explanations for the protective effect of severe Mg deficiency. When mice were maintained for 2 months after inoculation on a severely Mg-deficient diet and were then switched to a control diet, all survived and had low parasitaemias. After 1 month, these mice were rechallenged withB. hylomysciand 89% survived.
Toxoplasma gondii-structure variations of the antigen P30
Authors: Bonhomme A. , Thirion C. , Boulanger F. , Charton F. , Burlet H. , Pinon J. M. , Alix A. J. P. 
Published: June 2009

SUMMARYThe major surface immunodominant antigen (P30) ofToxoplasma gondiiwas purified by two methods (i) SDS–PAGE and (ii) immunoaffinity chromatography. The secondary elements within this protein were assessed by circular dichroism and spectra obtained were compared to those proposed by Manavalan & Johnson (1983). The results allowed us to determine an all β protein status for this antigen. This experimental result was in agreement with the predicted secondary structures deduced from the P30 primary sequence. Modifications in conformation according to pH and temperature were recorded without any change in immunoactivity. The epitope, which was always recognized by a monoclonal antibody against P30, could be a linear epitope.
Intermembrane lipid transfer duringTrypanosoma cruzi-induced erythrocyte membrane destabilization
Authors: Luján H. D. , Bronia D. H. 
Published: June 2009

SUMMARYThe ability ofTrypanosoma cruzito induce erythrocyte membrane destabilizationin vitrowas studied. Epimastigote forms adhered to human erythrocytes and caused fusion or lysis of the red cells, depending on the conditions of the interaction. Red cells were fused in the presence of calcium, while haemolysis was induced in the absence of the cation. Dextran 60 C facilitated fusion but delayed lysis. Optimum pH and temperature for fusion were 7·4 and 37 °C, respectively. Lipid alterations were produced in the plasma membrane of the red cell during the interaction with the parasite. A Ca2+-independent increase of lysophospholipids and free fatty acids was common to both the lysis and fusion processes. A relative increase of 1, 2-diacylglycerides was unique to the fusion process and these changes were dependent on Ca2+. The transfer of free fatty acids and lysophospholipids fromT. cruzito erythrocyte membranes was demonstrated using parasites pre-labelled with radioactive phospholipids. Pre-treatment of parasites with exogenous phospholipase A2abolished the fusogenicity, while lysis was increased. Neither fusion nor haemolysis occurred when the parasites were pre-treated with fatty acid free albumin, phospholipase A2inhibitors or when these compounds were present in the medium during the parasite-erythrocyte interaction. Our results suggest thatT. cruziinduces erythrocyte membrane destabilizationin vitroby transfer of lipid material in a calcium independent manner and that this ion is necessary for other membrane alterations that lead to erythrocyte fusion.
Comparative analysis of full-length antigen II/3 fromEchinococcus multilocularisandE. granulosus
Authors: Felleisen R. , Gottstein B. 
Published: June 2009

SUMMARYThe recombinantEchinococcus multilocularisantigen ll/3–10 is one of the most promising tools for immunodiagnosis of alveolar echinococcosis in human patients. Its nucleic acid sequence represents a part of theE. multilocularisgene encoding the metacestode antigen II/3, the former being basically present and expressed in bothE. multilocularisandE. granulosus. Most (94%) patients with alveolar echinococcosis respond to infection with a marked anti-II/3–10 IgG synthesis; in contrast, most of the cystic echinococcosis patients do not, for some reason, recognize the recombinant antigen. We tackled this problem by generating cDNA derived from bothE. granulosusandE. multilocularisfull length II/3 genes, performed by reverse transcription and PCR amplification. Sequence analysis revealed a very high degree of conservation of the primary sequence of the antigen II/3 in bothEchinococcusspecies. cDNA fragments were subcloned and expressed inE. colias fusion proteins withSchistosoma japonicumglutathione S-transferase. Recombinant proteins were affinity purified and comparatively assessed by ELISA with respect to antibody-binding characteristics. Sera from patients suffering from cystic echinococcosis showed no significant differences in reactivity with the antigens derived from eitherE. multilocularisorE. granulosus. Therefore, parameters other than some minor differences in the primary sequence seem to be responsible for the lack of antigen II/3 recognition in cystic echinococcosis.NoteNucleotide sequence data reported in this paper have been submitted to the GenBank®data base with the accession numbers U05573 and U05574.
Characterization of the cysteine proteinases of the common liver flukeFasciola hepaticausing novel, active-site directed affinity labels
Authors: McGinty A. , Moore M. , Halton D. W. , Walker B. 
Published: June 2009

SUMMARYThe excreted/secreted proteinases of adult and juvenileFasciola hepaticamaintainedin vitrowere found to hydrolyse the fluorogenic substrates Cbz-Phe-Arg- and Cbz-Arg-Arg-NHMec. This activity was demonstrated to have a classical cysteine proteinase inhibitor profile, with turn-over of both substrates being blocked by pre-incubation with E64 and peptidyl diazomethanes. The Cbz-Arg-Arg-NHMec hydrolysing activity of the mature fluke exhibited an alkaline stability not characteristic of its mammalian lysosomal counterparts. Further, the biotinylated affinity reagents biotin-Phe-Ala- CHN2and biotin-Phe-Cys(SBzyl)-CHN2were used to label and characterize these cysteine proteinases in terms of apparent molecular weight and subsite specificity. Adult fluke media were found to contain four species of molecular weights 66, 58, 50 and 25–26 kDa; juvenile media contained three species of molecular weights 66, 54 and 25–26 kDa. The major 25–26 kDa cysteine proteinase common to both stages was shown to have a subsite specificity similar to that of mammalian cathepsin B.
Plasmodium falciparum lacks sialidase and trans-sialidase activity
Authors: Clough B. , Atilola F. A. , Healy N. , Pereira M. E. A. , Bethell R. C. , Penn C. R. , Pasvol G. 
Published: June 2009

SUMMARYSialic acid on the red cell surface plays a major role in invasion by the malaria parasite Plasmodium falciparum. The NeuAc(α2,3) Gal motif on the O-linked tetrasaccharides of the red cell glycophorins is a recognition site for the parasite erythrocyte-binding antigen (EBA-175). Consequently, the interaction of P. falciparum and the red cell might share homology with that of the influenza virus. The cellular interactions of P. falciparum were examined for their sensitivity to 4-guanidino-2,3-didehydro-D-N-acetyl neuraminic acid (4-guanidino Neu5Ac2en), a potent inhibitor of influenza virus sialidase. Parasite invasion and subsequent development was unaffected by the sialidase inhibitor. The inhibitor did not affect rosette formation of parasite-infected erythrocytes with uninfected cells nor their cytoadherence to C32 melanoma cells. Furthermore, we were unable to confirm the presence of a previously reported parasite sialidase using sensitive fluorometric or haemagglutination assays, neither was any malarial trans-sialidase identified. We conclude that P. falciparum possesses neither sialidase nor trans-sialidase activity and that an inhibitor of influenza virus sialidase has no effect on important cellular interactions of this parasite.
Characterization of the first European isolate ofNeospora caninum(Dubey, Carpenter, Speer, Topper and Uggla)
Authors: Barber J. S. , Holmdahl O. J. M. , Owen M. R. , Guy F. , Uggla A. , Trees A. J. 
Published: June 2009

SUMMARYNeospora caninumis an apicomplexan, protozoan parasite, which causes severe disease in dogs and cattle. It has previously been isolated only in the United States. A 5-week-old Boxer pup with a progressive hindlimb paresis was diagnosed as suffering from neosporosis on the basis of clinical signs and the presence of anti-Neosporaantibodies in it, 2 litter-mates and its darn. Despite treatment with sulphonamides, the pup was euthanased 3 days later. The diagnosis of neosporosis was confirmed by immunohistochemical examination of muscle and CNS tissue sections from the pup. Parasites were isolated into Vero cell culture from the cerebrum, and confirmed asNeospora caninumby immunofluorescence with specific antibody, tachyzoite ultrastructure and 16S-like ribosomal RNA sequences. This isolate (designated NC-Liverpool) has been continuously passaged every 7–10 days. Its growth characteristics, ultrastructure and antigenic profile, as revealed by immunoblotting, have revealed no major differences from the American NC-1 isolate. Furthermore, no difference was seen when comparing the sequences of 16S-like ribosomal RNA and the ITS1 region of the two isolates.
Improved specificity ofTrypanosoma cruziidentification by polymerase chain reaction using an oligonucleotide derived from the amino-terminal sequence of a Tc24 protein
Authors: Taibi A. , Guevara-Espinoza A. , Schöneck R. , Yahiaoui B. , Ouaissi A. 
Published: June 2009

SUMMARYIn the present study, the diagnostic value ofTrypanosoma cruzirecombinant protein (Tc24) was examined. Although antibodies against Tc24 were detected during natural and experimentalT. cruziinfections, specificity studies revealed that sera fromT. rangeli-infected mice also recognized to some extent Tc24 protein. In addition, sera from Tc24-immunized mice reacted against a 21 kDa polypeptide inT. rangeliextracts. Detailed analysis of the antibody response against 20—40 peptide localized in the Tc24 amino-terminal domain suggests that this sequence is not expressed byT. rangeli21 kDa antigen. Therefore, the PCR reaction using oligonucleotides corresponding to a 20–26 peptide clearly demonstrated the specificity of the oligoprobes forT. cruziidentification. Positive signals were also found when using blood samples fromT. cruzi-infected mice. Taken together, these results suggest that the PCR-based 20–26 assay may be useful in the specific diagnosis of Chagas' disease.
Nuclear rDNA ITS sequence variation in the trematode genus Echinostoma: an aid to establishing relationships within the 37-collar-spine group
Authors: Morgan J. A. T. , Blair D. 
Published: June 2009

SUMMARYThe taxonomic history of members of the 37-collar-spine group within the genus Echinostoma has been very confused. We obtained DNA sequence data from the nuclear rDNA ITS1, 5·8S and ITS2 of 7 nominal species belonging to this group, Echinostoma trivolvis (Cort, 1914), E. revolution (Frölich, 1802), E. caproni Richard, 1964, E. liei Jeyarasasingam et al. 1972, E. paraensei Lie & Basch, 1967, two African isolates, E. sp.I and E. sp.II, and of one 28-collar-spined echinostome, E. hortense (Asada, 1926). Five of the eight species were clearly distinguishable using ITS data. Sequences from the remaining three taxa, E. caproni, E. sp.II and E. liei were identical to one another and the group containing these taxa was distant from other 37-collar-spine species on a phylogenetic tree. E. trivolvis and E. paraensei form a second, but less distinct group within the 37-collar-spine group. The resolution obtained using DNA sequencing will assist in the current reclassification of the group. It also provides a model for future work on sibling species.
Estimating the number of multiple-species geohelminth infections in human communities
Authors: Booth M. , Bundy D. A. P. 
Published: June 2009

SUMMARYInfections with Ascaris lumbricoides, Triclmris trichiura and the hookworm species are often found in the same communities and individuals. Hosts infected by more than one species are potentially at risk of morbidity associated with each infection. This paper describes the use of a probabilistic model to predict the prevalence of multiple-species infections in communities for which only overall prevalence data exist. The model is tested against field data, using log-linear analysis, and is found to be more effective at estimating the numbers of multiple infections involving hookworms than those involving only A. lumbricoides and T. trichiura. This latter combination of infections is found, in half the communities examined, to be more common than expected by chance. An age-stratified analysis reveals that the degree of interaction between these two infections does not alter significantly with age in the child age classes of a Malaysian population.
Characterization and localization of Schistosoma mansoni calreticulin Sm58
Authors: Khalife J. , Liu J. L. , Pierce R. , Porchet E. , Godin C. , Capron A. 
Published: June 2009

SummaryRecombinant Schistosoma mansoni calreticulin (SmCaR) was expressed in Escherichia coli, using the glutathione S-transferase fusion protein, and its Ca2+-binding capacity was determined. Results obtained by a 45Ca2+ overlay technique showed that Ca2+-binding site(s) were present in the recombinant CaR indicating that proper folding of the protein was obtained using this system. An antiserum raised against the recombinant SmCaR showed that the native protein (Sm58) was expressed in all stages of the life-cycle from cercariae to the adult worm and in the egg. However, SmCaR seems to be a developmentally regulated protein whose expression can be used to study the post-transformational differentiation of the schistosomulum. Localization of SmCaR demonstrated that the majority of SmCaR was expressed in the epithelia of the digestive duct and in the genital organs. These results suggest that SmCaR, by regulating the Ca2+ concentration, may play an important role during cell proliferation. Finally the presence of SmCaR in miracidia and in the genital organs suggests that the antibody response directed against this protein could interfere in egg production.