bluuebunny/crossref_metadata_2025_split huggingface dataset:
Patterns of macroparasite abundance and aggregation in wildlife populations: a quantitative review
Authors: Shaw D. J. , Dobson A. P. 
Published: June 2009

SUMMARYIn this paper we review the published literature on patterns of abundance and aggregation of macroparasites in wildlife host populations. We base this survey on quantitative analyses of mean burden and a number of measures of the degree of aggregation of parasite burdens between hosts. All major parasite and vertebrate host taxa were represented in the database. Mean parasite burden was found to be log-normally distributed, indicating that all parasite burdens are regulated to some degree. In addition, all but one of the parasitic infections were aggregated with respect to their hosts, and the relationship between log mean parasite burden and log variance was found to be very strong (R2= 0·87). That is, for a given mean parasite burden there are constraints on the degree of variation in individual host burdens. The aggregated nature of the parasitic infections is also apparent from other measures of the degree of aggregation: prevalence – mean relationships, and the negative binomial parameter,k. Using a relatively new technique for parasitological infection data – tree-based models, as well as traditional linear models – a number of the parasitic infections was found to be associated with systematically lower or higher parasite burdens. Possible biological explanations for these and other patterns are proposed.
Parasitic disease in amphibians: control by the regulation of worm burdens
Authors: Tinsley R. C. 
Published: June 2009

SUMMARYThis review considers three case studies based on macroparasites of anurans: (a) natural infections in the permanently-aquaticXenopus laeviswhich represent the worm burdens acquired, and the implications for pathology, when hosts are exposed to continuous, year-round, transmission; (b) the desert toad,Scaphiopus couchii, which experiences invasion very briefly each year and provides a simplified system involving only a single significant infection (Pseudodiplorchis americanus); (c) the mesicBufo bufowhich has been the subject of experimental laboratory studies designed to measure the effects ofRhabdias bufonisinfection on host growth, physical performance and survival. Experimental manipulation of bothScaphiopusandBufoprovide quantitative data on disease effects of macroparasites, including precise measurements of parasite-induced host mortality. Field data forXenopusandScaphiopusshow that, despite high initial worm burdens from efficient transmission, infection levels at parasite maturity are modulated below those leading to significant disease. Experimental data forScaphiopusandBufohave documented the time-course and magnitude of this decline in intensities, and there is circumstantial evidence forScaphiopusthat this regulation is host-mediated. Immunological studies onXenopusshow that disease effects of the pathogenicPseudocapillaroides xenopodisare exacerbated in thymectomised hosts and reversed by implantation of thymuses from MHC-compatible donors. Thus, whilst factorial experiments can demonstrate the potential of helminths to cause significant disease and mortality in anuran host-macroparasite interactions, powerful post-invasion regulation of worm burdens appears to exert a strong control of parasite-induced disease in natural host populations.
Antibodies to synthetic peptides based on band 3 motifs react specifically withPlasmodium falciparum(humanmalaria)-infected erythrocytes and block cytoadherence
Authors: Crandall I. , Sherman I. W. 
Published: June 2009

SUMMARYRabbit polyclonal and mouse monoclonal antibodies (Mabs) prepared against synthetic peptides patterned on exofacialloops 3 (amino acids 546–555) and 7 (821–834) of the human anion transport protein band 3 inhibited the cytoadherence ofPlasmodium falciparum-infected erythrocytes to C32 amelanotic melanoma cells. Mabs directed against exofacial loop4 (amino acids 628–642) did not inhibit adherence to a significant degree. The murine Mabs recognized onlyP. falciparum-infected erythrocytes suggesting that the epitopes of loops 3, 4 and 7 are normally cryptic in uninfected erythrocytes.
Ricin-resistant mutants ofLeishmania majorwhich express modified lipophosphoglycan remain infective for mice
Authors: Cappai R. , Morris L. , Aebischer T. , Bacic A. , Curtis J. M. , Kelleher M. , McLeod K. S. , Moody S. F. , Osborn A. H. , Handman E. 
Published: June 2009

SUMMARYGlycosylation variants of the virulentLeishmania majorclone VI21 were generated by mutagenesis withN-methyl-N-nitroso-N-nitroguanidine and selected using the galactose-specific lectinRicinus communisII (RCA II). Three mutants, 4B9, 1D1 and 1C12, which failed to bind RCA II, were found to have an altered expression of lipophosphoglycan (LPG), a molecule implicated in the attachment to host macrophages and survival within the phagolysosome. There were differences in the antigenicity, molecular weight and localization of LPG from mutant parasites as compared to V121. Expression of gp63, a surface molecule also implicated in attachment to macrophages, was unaltered. All 3 mutants caused disease when injected into genetically susceptible BALB/c mice but lesions developed at a much slower rate than those caused by the virulent V121 clone. This slow rate of lesion development did not correlate with promastigotes' ability to invade macrophagesin vitro. Karyotype analysis showed that there was a reduction in the size of chromosome band number 2 in all 3 mutants. The differences in LPG and chromosome band 2 were retained by mutant clones following passage through mice, suggesting that these phenotypes are stable. Although the mutant parasites were infective and caused lesions, the changed structure of the LPG appeared to influence the virulence of the parasites.
Prevalence and transmission of Toxoplasma gondii in wild brown rats, Rattus norvegicus
Authors: Webster J. P. 
Published: June 2009

SUMMARYPrevalence of Toxoplasma gondii within 6 UK farmstead wild rat populations, and 1 population maintained within a captivecat-free environment for 2·5 years, was examined. The mean prevalence found was 35% (n = 235), which is more than 3 times as high as all other wild rat prevalence levels previously reported in the UK. There were no significant age, sexor site differences in prevalence between or within populations irrespective of habitat type or presence of cats. Toxoplasma was also maintained within the captive rat population in the absence of cats at a prevalence, intensity, age and sexdistribution similar to that of the farmstead rat populations. These results suggest, firstly, that Toxoplasma can beperpetuated within wild rat populations without the sympatric presence of cats and secondly, that the congenital route isthe predominant route of transmission in wild rats. This study concludes that wild rats represent a significant and persistent wildlife intermediate host reservoir for toxoplasmosis.
Inhibition ofPlasmodium falciparumlysophospholipase by anti-malarial drugs and sulphydryl reagents
Authors: Zidovetzki R. , Sherman I. W. , Prudhomme J. , Crawford J. 
Published: June 2009

SUMMARYThe activity of lysophospholipase of human erythrocytes increased by about 3 orders of magnitude upon infection withPlasmodium falciparum. The apparentKmfor hydrolysis of lysophosphatidylcholine by this enzyme was 50 ± 7μM and the apparentVmax6·8±0·6 nmol/h × 106cells. The activity was Ca2+independent and had a broad pH maximum at pH 8. The enzyme was insensitive to such anti-malarials as mefloquine and arteether and was only weakly inhibited by chloroquine, with a 50% inhibition concentration (IC50) of 70 mM. The anti-malarials quinine and quinacrine were more efficient inhibitors, with IC50s of 2·6 mM and 0·7 mM, respectively. The sulphydryl agentsp–hydroxymercuribenzoate (pHMB) and thimerosal were considerably more potent, inhibiting the plasmodial lysophospholipase with IC50s of 18 μM and 10 μM, respectively. When present at 10 μM prior to invasion, both pHMB and thimerosal arrested the growth and reinvasion capacity ofP. falciparumin culture. In a synchronizedP. falciparumculture the continuous presence of 5 μM thimerosal dramatically decreased total parasitaemia and, within 4 days, totally abolished the capacity of the surviving parasites to reinvade. Thus the plasmodial lysophospholipase may represent a potential new target for anti-malarial chemotherapy.
Immunochemical studies on the cercarial-specific calcium binding protein ofSchistosoma mansoni
Authors: Ram D. , Romano B. , Schechter I. 
Published: June 2009

SUMMARYStage-specific expression of the mRNA encoding the cercarial-specific 8 kDa CaBP has been described previously. To gain information on possible function(s) of this protein we raised antibodies to the CaBP in rabbits immunized with a CaBP-TrpE fusion protein synthesized in bacteria. Western blots showed high levels of CaBP in cercariae and 3 h schistosomula, trace amounts in 24 h schistosomula, and none in miracidia sporocyst and adult worm, as found for the mRNA. The CaBP molecule has a short half-life (≤4 h) similar to that of the mRNA. Other experiments demonstrate that the CaBP may interact with a putative target molecule in a calcium-dependent manner to form a complex of 45 kDa. Immunogold electron microscopy showed CaBP in selected regions of cercariae and 3 h schistosomula: tegument, head gland, subtegumental cells, flame cells, intestinal wall and the body-tail junction. Other investigators have shown that the head gland and subtegumental cells synthesize and translocate granules to the tegument during transformation from cercariae (living freely in water) to schistosomula (residing in vertebrate host). These observations and the time-course of CaBP detection suggest that the CaBP synthesized in the head gland and subtegumental cells is translocated to the tegument where it plays a role in tegument modifications required for adaptation to parasite life in the host. CaBP was not found in muscles and mitochondria, suggesting that it is not involved in the rapid motility and aerobic metabolism characteristic of cercariae.
Molecular genetic characterization of the cervid strain (‘northern form’) ofEchinococcus granulosus
Authors: Bowles J. , Blair D. , McManus D. P. 
Published: June 2009

SUMMARYWe have used a number of molecular genetic approaches to characterize the cervid strain (‘northern form’) ofEchinococcus granulosus.PCR–RFLP analysis of the nuclear ITS1 region of the rDNA repeat can readily distinguish the cervid form from other strains ofE. granulosus. The complexity of the RFLP patterns obtained suggests that a number of distinct ITS1 types are present in this strain which may represent an inter-strainE. granulosushybrid. Mitochondrial CO1 sequence of the cervid genotype was ambiguous at 18 positions and closely resembles a cluster of previously characterizedE. granulosusgenotypes, G1 (common, domestic sheep)/G2 (Tasmanian sheep)/G3 (buffalo). In contrast, mitochondrial ND1 sequence, although unique, suggests that the cervid form is most similar to strains represented by the G6 (camel)/G7 (pig) genotypes. We assume that the CO1 and ND1 sequences obtained for the cervid genotype are linked in a single mitochondrial genome although this is difficult to explain if conventional molecular genetics of mitochondrial DNA are assumed. Based on its unique ND1 sequence and ITS1 PCR–RFLP pattern, the cervid strain appears to represent a distinct genotype (designated G8) ofE. granulosus.
Microscopical observations on immune precipitates formedin vitroon the surface of hymenolepid tapeworms
Authors: Hoole D. , Andreassen J. , Birklund D. 
Published: June 2009

SUMMARYFour-day-old worms of the tapewormsHymenolepis microstoma,H. diminutaandH. nanaand newly excystedH. microstomawere exposed in vitro at 37 °C to immune serum from mice infected for 4–1 2 weeks withH. microstoma. Worms were fixed for electron microscopy after intervals of 5 min to 96 h. Within 10–15 min an homogeneous precipitate occurred between the microtriches of 4-day-oldH. microstomaandH. nana, while on some areas ofH. microstomathe precipitate extended distal to the microthrix border and contained small vesicles (30 nm in diameter) and shed microtriches. InH. diminutaprecipitates were not found until 2 h post-incubation. The thickness of the precipitate and the number of small vesicles and shed microtriches increased with time after incubation. Since a similar precipitate occurred on worms kept in complement-depleted immune serum, antibodies alone may induce immune damage. The precipitate on newly excystedH. microstomalacked microthrix fragments. After 48 h an extensive precipitate was found protruding from the rostellar glands on someH. microstoma, and within the culture vessel. Antibodies may therefore be complexing with tapeworm secretory products.
Heterogeneity in patterns of malarial oocyst infections in the mosquito vector
Authors: Medley G. F. , Sinden R. E. , Fleck S. , Billingsley P. F. , Tirawanchap N. , Rodriguez M. H. 
Published: June 2009

SUMMARYOocyst prevalence and intensity have been recorded in 349 laboratory infections ofAnopheles stephensiwithPlasmodium berghei. Intensity and prevalence of infection are shown to be predictably related. The structure and heterogeneity in the infections has been analysed with the objective of describing the biological mechanisms by which the observed negative binomial oocyst distributions are generated. The analysis has revealed that the most likely processes lie within the population dynamic events of malaria within the mosquito, namely gametogenesis, fertilization and mortality. The distribution is similar in allPlasmodium– mosquito combinations examined so far, whether they are of laboratory (P. gallinaceuminAedes aegypti) or field (P. vivaxinAn. albimanusandP. falciparuminAn. gambiae s.l.andAn. funestus) origin. Further we conclude that there is competition between parasites in the vector. Oocyst frequency distribution analysis shows that under natural conditions of transmission intensity, and even under the best laboratory conditions, significant numbers (> 10%) offullysusceptible mosquitoes will not be infected under conditions where the mean infection is as high as 250 oocysts. Failure to infect is not therefore an absolute indicator of refractoriness. In assessing transmission data it is shown that sample sizes should not be less than 50, and ideally 100 mosquitoes, if reliable data are to be obtained. In the field it is suggested that difficulties in determining the low natural intensity of oocyst infections indicate that prevalence estimates are a useful and accessible parameter to measure. In determining the impact of transmission blocking mechanisms we predict that under conditions where high oocyst intensities prevail, large reductions in intensity will be required before a reduction in prevalence can be expected i.e. here it will be necessary to measure intensity of infection. Conversely, under conditions where low oocyst intensities prevail, a rapid reduction in prevalence will occur with little concurrent reduction in intensity i.e. prevalence determination will be the more sensitive estimate.
Immunization of pigs against infection with Schistosoma japonicum using ultraviolet-attenuated cercariae
Authors: Shi Y.-E. , Jiang C.-F. , Han J.-J. , Li Y.-L. , Ruppel A. 
Published: June 2009

SUMMARYSince pigs are important in the zoonotic transmission of schistosomiasis japonica in China, a veterinary vaccine might contribute to the control of the disease in humans. Pigs were immunized with three doses each of 10000 cercariae of Schistosoma japonicum attenuated with ultraviolet light (400 μWatt·min/cm2). The experiment was performed with portable irradiation equipment in a rural area of the Hubei Province (P.R. China). A challenge infection of 1000 untreated cercariae was given 2·5 or 6 months after the last immunization, and age-matched naive pigs were challenged as a control. Immunized pigs developed about 90% resistance against the challenge. The liver egg load of these animals was reduced by over 90%. Less than 0·01 % of the immunizing cercariae developed to adult parasites and the vaccination had no apparent adverse influence on the pigs' health.
Mechanisms involved in the loss or antibody-mediated adherence of macrophages to lung-stage schistosomula ofSchistosoma mansoni in vitro
Authors: Lawson B. W. L. , Bickle Q. D. , Taylor M. G. 
Published: June 2009

SUMMARYSera from rabbits vaccinated with irradiated cercariae mediated cell (P388D1or mouse peritoneal macrophage) adherence to lung-stage schistosomula (LS) but such antibody-mediated cell adherence was short-lived in contrast to cell adherence to mechanically transformed schistosomula (MS). Thus LS lost 50% of their adherent cells within 3–6 h in culture and up to 90% by 24 h, whereas adherence to MS was undiminished during this time. Rapid loss of adherent cells was unique to schistosomula that had developed to the lung stage because schistosomula recovered from the skin up to 3 days post-infection did not exhibit the rapid cell loss shown by 3-day LS. To determine whether cell loss was caused by loss of surface antigenicity during culture LS were cultured on their own for up to 24 h and at various intervals samples of schistosomula were tested for antigenicity by addition of immune serum and cells. Levels of adherence to both MS and LS were maintained throughout the incubation period. When antibody-opsonized schistosomula were washed and indicator cells added at progressive intervals, persistence of adherence was again demonstrated, showing that antibody binding to LS had not promoted surface antigen loss or degradation of bound antibody. It was then shown, by adding fresh macrophages to cultures up to 24 h old that LS which had lost their adherent cells nevertheless retained bound antibody, and comparison of adherence of ‘used’ and ‘fresh’ cells to MS and LS showed that the cytoadherence properties of macrophages were not significantly reduced during their culture with LS from which cells had been lost. Cell loss was shown to be dependent upon protein synthesis by LS since cell loss was significantly reduced when the schistosomula were pre-incubated in puromycin or actinomycin D. Transient cell adherence to LS may comprise an important immune evasion stratagem by schistosomula.
Epidemiology of trypanosome infections of the tsetse fly Glossina pallidipes in the Zambezi Valley
Authors: Woolhouse M. E. J. , Hargrove J. W. , McNamara J. J. 
Published: June 2009

SUMMARYThe epidemiology of trypanosome infections of Glossina pallidipes was studied at a riverine site in the Zambezi Valley, Zimbabwe for a period of 13 months. Over 9000 flies were captured using a single trap. These flies were dissected, screened for trypanosome infection, sexed, and aged using both wing fray and (for females) ovarian category indices. Midgut infections were identified to species using recently developed DNA probes. The overall prevalence of mature infections was 5·5%, comprising 3·1% Trypanosoma vivax-type and 2·4% T. congolense-type (which included very low prevalences of T. brucei, T. simiae and another Nannomonas species). The prevalence of infection increased with age. For T. vivax-type infections in flies aged by ovarian category this relationship could be described by a simple ‘catalytic’ model assuming a constant per capita rate of infection. For T. congolense-type infections this model tended to over-estimate prevalence in older age classes, implying that the rate of infection decreases with age, and/or that infected flies have higher mortality rates, and/or that a significant fraction of the population is resistant to infection. Prevalences of infection also varied between months. This variation was more marked for T. vivax-type infections and was negatively correlated with both temperature and rainfall. The shape of the age-prevalence relationship, however, did not vary significantly between months. These observations are not fully explained by variation in the age-structure of the tsetse population and are consistent with temporal variation in the rate of infection (rather than in the trypanosome developmental period or in effects of infection on fly mortality). Possible causes of this variation are discussed.
Spatio-temporal structure of the communities of helminths in the digestive tract of Sciaena umbra L. 1758 (Teleostei)
Authors: Holmes J. , Bartoli P. 
Published: June 2009

SUMMARYThe helminth community in the digestive tract of the sedentary predatory fish, Sciaena umbra, near the Scandola Nature Reserve, Corsica, consists of 5 species of digeneans. Anoiktostoma coronatum (in the rectum) and Metadena pauli (in the intestine) were found in almost all the fish, and in high numbers; they are considered core species. Distomum aloysiae, Pleorchis polyorchis (both in the intestine), and Stephanostomum bicoronatum (in the rectum) were relatively uncommon, usually found in small numbers, and are considered satellite species. The two core species were very abundant in June, when the size of their populations was strongly correlated with the size of the host fish. At this time, M. pauli was found mainly in the duodenum, but in high populations was spread throughout the intestine (s. strict.). Both species were much less abundant in October, their populations were less dependent on host size, and M. pauli was more limited to the anterior intestine. Pleorchis polyorchis and Distomum aloysiae were more frequent in October, were found predominately in fish with few M. pauli, and were found posterior to M. pauli, suggesting some interactions between these species. Stephano-stomum bicoronatum showed no seasonal patterns, and no apparent interactions with A. coronatum.
Asparaginyl endopeptidase activity in adultSchistosoma mansoni
Authors: Dalton J. P. , Hola-Jamriska L. , Brindley P. J. 
Published: June 2009

SUMMARYSequence comparisons have recently shown that theSchistosoma mansoniprotein Sm32 is similar to asparaginyl endo-proteinases, a novel family of cysteine proteinases, of which the legumains rom legumes are the best characterized. By synthesizing and employing fluorogenic peptide substrates for the specific detection of asparaginyl endopeptidases, we have identified this type of activity in extracts of adultS. mansoni. TheS. mansoniactivity is similar to that of the legumains in its substrate specificity and sensitivity to thiol inhibitors, but differs in its pH and temperature optima for activity. In contrast, unlike the legumains, the schistosome asparaginyl endopeptidase activity is not activated by the reducing agent dithiothreitol. As suggested for legumains, Sm32 may function in the post-translational modification processes that regulate the activity of other molecules.
Examination of the Steinernema feltiae (Site 76 strain) infection interaction with the Galleria mellonella host, using an infection model
Authors: Bohan D. A. , Hominick W. M. 
Published: June 2009

SUMMARYUsing a simple infection model the infection interaction of Steinernema feltiae (Site 76 strain) Filipjev and Galleria mellonella L. was investigated under laboratory conditions. The model analyses showed that the infection interaction was consistent with a proportion of the S. feltiae infective stages being infectious and, alone amongst the infective-stage population, being capable of infection. The investigation also showed that the infection behaviour of the infectious stages could be reduced to a slightly overdispersed probability of transmission. The importance of these findings with respect to the quantitative description and explanation of infection are discussed.