bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunological realtionships during primary infection withHeligmosomides polygyrus(Nematospiroides dubius): expulsion of adult worms from fast responder syngeneic and hybrid strains of mice
Authors: Wahid F. N. , Robinson M. , Behnke J. M
Published: June 2009

The time-course of low and high intensity primary infections withHeligmosomoides polygyruswas monitored in SJL and SWR mice, both of which usually expel worms within 7 weeks of larval administration. Worm expulsion in these strains was not dependent on the intensity of infection, with low and high intensity worm burdens being lost within the same period of time. The ability to expel worms rapidly was inherited in a dominant manner in F1offspring of SJL or SWR mice mated with C57Bl10mice; the latter being a strain in which no loss of worms was evident within 10 weeks of infection. However, neither (SJL × C57Bl10)F1nor (SWR × C57Bl10)F1mice expelled worms as rapidly as the parental SJL and SWR strains. (SWR × B10G)F1[H-2q] mice eliminated worms faster than (SWR × C57Bl10)F1[H-2bq], suggesting that the b haplotype had a moderating influence on the expulsion process. In fact (SWR × B10G)F1mice showed a significant reduction in worm burdens by week 4 but by weeks 6–8 the rate of worm loss had slowed considerably. In contrast, SJL and SWR mice, whilst initiating rejection slightly later, (after week 4) expelled all worms within the following 2 weeks. Thus two distinct patterns of response were observed among the fast responder strains as exemplified by SWR and SJL mice on the one hand and (SWR × B10G)F1on the other. Our results support the hypothesis that the course of a primary infection withH. polygyrusis influenced by multiple host gene loci, some of which are encoded within the MHC. SJL and SWR mice probably have similar if not identical gene combinations at loci which determine a fast responder phenotype, distinguishing them from the other mouse strains which have been studied.
Differences in numbers and inequalities in mass and fecundity during the egg-producing period for Raphidascaris acus (Nematoda: Anisakidae)
Authors: Szalai A. J. , Dick T. A.
Published: June 2009

Maturity, mass and sex were determined for individual Raphidascaris acus from northern pike, Esox lucius from Dauphin Lake, Manitoba. Length, width and total fecundity of female worms; seasonal changes in worm numbers, growth and maturity; and inequalities in mass and fecundity were quantified for 8 sample periods between April and September. Recruitment of R. acus is most rapid in early spring and continues throughout summer. An accumulation of larvae over winter leads to a peak in the number of gravid worms in spring, while increased feeding by post-spawning pike on yellow perch, Perca fluviatilis, leads to lower levels of gravid worms throughout summer and early autumn. Gravid worms found in spring versus summer were similar with respect to all measured variables and do not appear to be from genetically distinct populations. The strength of the correlation between fecundity and mass for worms was variable between pike and between sample periods, and only weakly correlated when the data were pooled. Much of this variation could be attributed to continued growth of gravid worms after maturation. Worms found in June were smaller, less fecund and less variable and inequalities in mass and fecundity measured using Gini coefficients (GCs) and Lorenz curves (LCs) were most similar at this time. For all other sample periods inequality in fecundity was greater than the corresponding value for mass. Similarity between GCs based on mass and fecundity was maximum when the coefficient of variation (C.V.) for mass was greater than the corresponding C.V. for fecundity. These observations suggest that one must be cautious when applying GCs and LCs to the analysis of parasite populations.
Responses to larvalTaenia taeniaeformisin mice with severe combined immunodeficiency (scid)
Authors: Ishiwata K. , Oku Y. , Ito M. , Kamiya M.
Published: June 2009

Responses toTaenia taeniaeformisinfection were studied in mice with severe combined immunodeficiency (scid), which lack functional T and B lymphocytes. In the early phase of infection, accumulation of polymorphonuclear leucocytes (PML) occurred around the larvae in the liver ofscidmice and their immunocompetent counterparts, C.B-17, (a BALB/c strain, genetically resistant to this parasite). PML accumulation continued until encapsulation of developing larvae by fibroblasts (14 days p.i.), and subsequent fibrosis resulted in granuloma formation. No infiltration of eosinophils or macrophages around larvae was observed inscidmice prior to granuloma formation, while in C.B-17 mice infiltration was observed as early as 5 days p.i., when specific antibodies could not be detected in the circulation. Most larvae were destroyed by 14 days p.i. in C.B-17 mice. Inscidmice the larvae survived but the host capsules (cysts) were thin and most contained blood at 42 days p.i. In these cysts, inflammatory cells were observed on the larval surface and in invaded parasite tissue. Hepatocyte coagulation necrosis adjacent to larvae was commonly found in C.B-17 mice by 5 days p.i., while it did not occur inscidmice throughout these experiments. These results suggest that in host responses to larvalT. taeniaeformis, PML accumulation and encapsulation by fibrosis are T and B cell independent, while eosinophil and macrophage infiltration, as well as resistance to infection, are T and/or B cell dependent. Additionally, there may be an association between host cell necrosis around larvae and T and/or B cell responses.
Isolation and characterization of polysomes from Trypanosoma brucei
Authors: Cordingley J. S. , Turner M. J.
Published: June 2009

The isolation of polysomes in bulk from bloodstream forms of Trypanosoma brucei is described. The polysomes are active in in vitro protein synthesis in the presence or absence of initiation inhibitors. Nascent variant surface antigen (VSA) has been detected on these polysomes using purified radio-iodinated antibody. EDTA-induced ribosomal sub-units and their large rRNA's are characterized. The 26S rRNA is nicked to produce 2 molecules which are both smaller than the 195 rRNA of the small sub-unit which is larger than that found in the majority of eukaryotic small sub-units.
Reactivity of anti-tegument monoclonal antibodies with target epitopes in different worm tissues and developmental stages ofSchistosoma mansoni
Authors: Riengrojpitak Suda , Vojvodic Maria , Boot C. , Wilson R. A.
Published: June 2009

Sixteen monoclonal antibodies (MABs) were selected for their reactivity with adult schistosome tegument. The distribution of target epitopes in different tissues of the adult and in various developmental stages was investigated by indirect immunofluorescence. The distinct patterns of reactivity of the MABs permitted their classification into 9 groups. The distribution of epitopes in larvae, particularly 3 h schistosomula, generally mirrored that in adults. A change in distribution of epitopes coincided with transformation from cercaria to schistosomulum providing a marker for this process. Two MABs reacted with surface membranes of intact cercariae, and 5 with the surfaces of intact 3 h schistosomula. The target epitopes of these 5 MABs were present in the tegument of adults, but not accessible externally. These observations suggest masking of antigens, not shedding, in the course of development. Indeed, no MAB reacted with intact lung or liver worms unless they were damaged. Three MABs reacted with membranes of the tegument and most other tissues, implying properties in common. Evidence for shared functions between epithelia was provided by the reactivity of 2 MABs with the tegument and protonephridia. Eight MABs bound both to the tegument and its cell bodies. Since the latter contains the machinery for protein synthesis, it is difficult to explain why 5 MABs bound to the tegument alone. Little cross-reactivity was found with the tissues of the tapewormHymenolepis, rather more with the closely relatedSchistosoma japonicum. It was concluded that tegument antigens are to a degree tissue specific but definitely not stage specific.
Role of hypochlorous acid inTrypanosoma musculikilling by phagocytes
Authors: Vincendeau P. , Daulouède S. , Veyret B.
Published: June 2009

Trypanosoma musculiare readily killed when phagocytosed by mononuclear phagocytes but the nature of the mediators of this cytotoxicity is unclear. Among the most potent mediators are oxygen-derived species. The generation of chemilumine-scence (CL) by peritoneal macrophages from 12 dayT. musculi-infected mice, which phagocytose and kill parasites when opsonizing antibodies are present, was recorded in the presence of antibody-coated trypanosomes. Taurine, a specific quencher of hypochlorous acid (HOCl) inhibited CL production by peritoneal macrophages, showing that HOCl is produced during phagocytosis ofT. musculi.In vitro, HOCl alone exerted a powerful trypanocidal activity which was inhibited in the presence of specific quenchers. The role of HOCl generated by phagocytes in trypanosome killing was studied using granulocytes which produce more oxygen-derived species than macrophages when stimulated. Phorbol myristate acetate-triggered granulocytes can destroyT. musculiand trypanosome killing is inhibited in the presence of taurine. These data demonstrate that HOC1 produced by phagocytes can effectively destroyT. musculi.
Host predisposition to trichuriasis: the mouse — T. muris model
Authors: Else K. J. , Wakelin D. , Roach T. I. A.
Published: June 2009

Predisposition to trichuriasis in mice is reflected in the inability of certain strains, or certain individuals within strains, to express protective immunity. Poor responders fail to expel worms and harbour chronic patent infections. The mechanisms underlying this phenomenon were studied in poor responder mice challenged after abbreviated or prolonged primary infections. Mice exposed to a complete primary infection were fully susceptible when challenged after the removal of the primary infection by anthelmintic. Failure to expel either infection suggests (a) that non-responsiveness to a primary infection does not reflect an inability to expel worms of a certain size, i.e. is not a consequence of the speed of the immune response in relation to parasite growth and (b) that non-responsiveness is long-lasting. Challenge after abbreviation of primary infections at different stages of worm development showed that persistence of larvae beyond day 21 was critical in determining poor response to reinfection. By inference the same conclusion can be drawn about the inability of such mice to expel primary infections. Serological analysis suggested a relationship between low antibody titres, restricted antigen recognition profiles and resistance to infection. It is suggested that the later stages of parasite development are immunosuppressive; the implications for human trichuriasis are discussed.
Mechanisms of immunity to malaria and the possibilities of a blood-stage vaccine: a critical appraisal
Authors: Butcher G. A.
Published: June 2009

Resistance developed by the immune system in response to blood-stage malaria is complex in nature, involving humoral and non-antibody effector mechnisms. Different species of malarial parasites may vary in their ability to elicit, or their susceptibility to, those immune effectors. This complexity is enhanced by the different results obtained in vaccinated as opposed to drug-controlled infections. It is therefore important that some attempt be made to unravel these interactions. This is particularly so when we have to decide on methods for assessing the potentiality of antigens to induce protective immunity. In this review the limitations of somein vitroassays of immunity, as well as those of various host–parasite models, are discussed. The relative importance of cell-mediated and humoral immunity in laboratory models and natural infections is also considered in the context of vaccine development.
The effect of the suckling stimulus on the migration of Strongyloides ratti in lactating rats
Authors: Wilson P. A. G.
Published: June 2009

The number of adult Strongyloides ratti which developed in the guts of lactating rats after subcutaneous injection of 4000 L3 on day 18–20 post partum was taken to be a measure of the relative importance of alternative larval routes. When injection was carried out at different times before and after weaning, larvae were diverted from a route bypassing the gut in nursing mothers to one leading to the gut (‘migration reversal’) in mothers without young in a period of less than 10 h. Migration reversal was mostly completed in lactating females injected at the time of weaning when compared with nulliparous controls. A stimulus-sensitive period shortly after injection, predicted from these dynamics, was demonstrated. Worms injected into lactating females 10 h after removal from their pups showed complete migration reversal. In similarly treated rats, given 1 h suckling 3 h after injection, migration reversal was practically abolished. These inter-relationships, in conjunction with earlier findings, are used to deduce the possible humoral mechanisms involved and to develop a working hypothesis to account for larval orientation based on features of the mammalian pulmonary microvasculature.
Strongyloides ratti: relative importance of maternal sources of infection
Authors: Zamirdin Mohamed , Wilson Peter A. G.
Published: June 2009

Milk-borne infection is demonstrated for Strongyloides ratti in rats, accounting for 32% of the combined worm burden of non-immune mothers plus their offspring at a standard dose of 4000 L3. Migrating larvae are ‘switched’ to the mammary gland about 3 days prepartum in advance of the final events of lactogenesis in the host at 30 h prepartum. Larvae take between 24–48 h to reach the milk after injection.

The ‘take’ in lactating rats was half that in virgin controls and pregnant animals before day 3 prepartum, but this discrepancy was not made up by the number of worms in the litter, the combined figure for mothers and offspring still being only 75% of the potential judged by the controls.

Prenatal infection did not occur in these experiments, which involved carefully controlled cross-fostering between infected and uninfected mothers. Injections of larvae covered the period between 12 days to 20 h prepartum in different animals. This route is possible under other circumstances, although it is considered unlikely in non-immune females since there was no evidence of larval dormancy in maternal tissue.
Suppression ofTaenia crassicepsduring concurrent infections withMesocestoides cortiin mice
Authors: Joysey H. S.
Published: June 2009

Parasite burden (by volume) was measured in female mice of three strains given single or concurrent infections ofMesocestoides cortiandTaenia crassiceps. Significant suppression ofT. crassicepsvolume was observed over a range ofM. cortiinocula and occurred irrespective of whetherM. cortiwas introduced before or after infection withT. crassiceps. Suppression ofT. crassicepsvolume was greatest with larger inocula ofM. cortiand with increased duration ofM. cortiinfection. No significant difference was found in the intraperitoneal volume ofM. cortifrom mice given single or simultaneous concurrent infections ofM. cortiandT. crassiceps. WhenM. cortiwere inoculated into mice with an established infection ofT. crassicepsa significantly smaller volume ofM. cortiwas retrieved at post-mortem from the peritoneal cavities of these mice, than from mice given justM. corti.
Gametocyte sex ratios as indirect measures of outcrossing rates in malaria
Authors: Read A. F. , Narara A. , Nee S. , Keymer A. E. , Day K. P.
Published: June 2009

The frequency of recombination between unlike genotypes is central to understanding the generation of genetic diversity in natural populations of malaria. Here we suggest a way of investigating the problem which could complement conventional biochemical approaches to the population genetics of malaria. Sex allocation theory is one of the most successful areas of evolutionary biology. A well-supported prediction is that progressively less female-biased sex ratios are favoured with more outcrossing; equal numbers of males and females being evolutionarily stable in randomly mating outbred populations. We present a simple game theory model to support the idea that outcrossing rates in malaria will be correlated with the sex ratio of gametocytes in the peripheral blood of vertebrate hosts. Blood films from epidemiological surveys and culture-adapted isolates from Madang Province, Papua New Guinea, were used to estimate average gametocyte sex ratio of Plasmodium falciparum in the area. The geometric mean proportion of males in the population was 0.18 (95% confidence limits: 0.15–0.22). From our model, we estimate that, on average, 36% of zygotes are the result of outcrossing. This estimate assumes that most microgametes released following exflagellation are capable of fertilization. If, on average, fewer than about 70% of microgametes are capable of fertilization (as is the case in at least one other species of Plasmodium), the observed sex ratio would be consistent with between zero and 36% of zygotes being the result of outcrossing. These estimates suggest that there is usually a numerically dominant genotype in the gametocyte population in a blood meal, and that a considerable amount of selfing is occurring in P. falciparum populations in the Madang region, even though it is an area of intense year-round transmission.
A model to assess survival mechanisms of parasites in a genetically defined host system
Authors: Arnason A. N. , Dick T. A. , Wassom D. L.
Published: June 2009

We examined a host system (Peromyscus maniculatus) in which a single autosomal gene controls susceptibility or resistance to infection by the cestode parasite Hymenolepis citelli. Parasite deaths of both primary and secondary (challenge) infections were examined, using a probabilistic model, to see if deaths were random and uncorrelated within each genotype. Within susceptible hosts, post-patent survival of primary worms was not random and heterogeneity was due to among-host effects rather than parasite-age effects, suggesting a second genetic or immunological process. Secondary infections in susceptible hosts appear to be lost randomly, independent of primary infection age or burden. The loss rate is similar to that for primary worms. The lack of correlation or alteration in (susceptible) host response to primary and secondary infections suggests that the latter are eliminated by a process that differs from that acting on primary worms. In resistant hosts, parasite survival rates suggest that the immunological process elicited by the primary infection also acts to eliminate the secondary infection more rapidly. Suggestions are made for improving experimental methods when dealing with mixed genotype populations. Experiments should permit direct estimation of genotype frequency and of parasite death rates within each genotype. This separation of host type is particularly important when studying correlation of successive worm burdens since any host or treatment mixture (genotype, age, sex, size or infection dose) may induce correlations that could be mistakenly interpreted.
Acquired resistance to Onchocerca lienalis infections in Simulium ornatum Meigen and Simulium lineatum Meigen following passive transfer of haemolymph from previously infected simuliids (Diptera, Simuliidae)
Authors: Ham P. J.
Published: June 2009

This study describes experiments which demonstrate the presence of a parasite-induced or derived factor in the haemocoel of Onchocerca lienalis-infected simuliids. Haemolymph, when transferred from previously infected donor flies to previously untreated recipient flies, using fine glass needles, confers protection against a subsequent challenge to the recipients. In three trials using Simulium ornatum sl. or S. linealum, significant levels of protection in ‘immunized’ compared to ‘challenge control’ groups were achieved (84% and 81% with S. ornatum sl. and 85% with S. lineaturm). This is despite the fact that the worm burdens of the infected donor groups in the three trials were very different (means of 33·1 and 3·4 larvae/fly with S. ornatum sl. and 1·6 larvae/fly with S. linealum). The use of sham-operated and bentonite-inoculated control groups demonstrate that this effect is not merely a non-specific reaction to trauma, but is probably parasitic in its derivation. The use of double infections separated by 4 days shows that the donor flies have themselves probably acquired resistance to O. lienalis. Frequency distributions of O. lienalis burdens in individual flies show that there is a shift froni a normal to a skew distribution when comparing ‘challenge control’ flies with ‘immunized’. This possible acquired resistance could have important implications in the transmission of forest and savanna human onchocerciasis by the Simulium damnosum complex.
Lamellar membranes associated with rhoptries in erythrocytic merozoites ofPlasmodium knowlesi: a clue to the mechanism of invasion
Authors: Bannister L. H. , Mitchell G. H. , Butcher G. A. , Dennis E. D.
Published: June 2009

In merozoites ofPlasmodium knowlesi, rhoptries have a dense substructure of fine (2·5 nm diameter) granules and short rods. These are not altered by lipid extraction, and stain with ethanolic phosphotungstate indicating a proteinaceous composition. Various types of fixation also show multilamellar whorls with a periodicity of 5–7 rim in the tips of rhoptries or extruded at the merozoite apex. In merozoites fixed during invasions of red cells, membrane continuity typically occurs between the rim of the rhoptry canal and the red cell membrane, but where this contact has apparently been lost, extensive membranous whorls and blebs are often found at the apex of the parasite. Similar structures occur at the spices of merozoites within late-stage schizonts. It is suggested that the same mechanism which generates these lamellae forms the parasitophorous vacuole by inserting membranous elements formed by the parasite into the red cell membrane, so causing its invagination. A similar mechanism may be responsible for the release of merozoites from the late-stage schizont.
DNA probes for the detection of Babesia caballi
Authors: Posnett E. S. , Ambrosio R. E.
Published: June 2009

A genomic library of Babesia caballi DNA was constructed in the plasmid vector pUC13. The specificity of the clones for B. caballi was established by the lack of hybridization to Babesia equi, Babesia bovis, Babesia bigemina and equine DNA. Two probes, pBC11 and pBC191, were isolated that could detect 0·25 ng and 0·125 ng of B. caballi DNA, corresponding to a parasitaemia of 0·12% and 0·06% respectively. pBC191 could detect B. caballi parasites in the blood of an experimentally infected horse as well as in naturally infected horses.
An analysis of survey measurements of tsetse challenge to trypanotolerant cattle in relation to aspects of analytical models of trypanosomiasis
Authors: Rawlings P. , Dwinger R. H. , Snow W. F.
Published: June 2009

The recent development of analytical models of trypanosomiasis has increased the general applicability of models to the strategic control of the disease. An analysis of detailed data on tsetse abundance and infection rates and trypanosome prevalence in village-based trypanotolerant cattle over 4 years in The Gambia showed that seasonal patterns of abundance in Glossina morsitans-infested areas were consistent, and that the rates of trypanosome infection remained relatively unchanging. However, there were two distinct seasonal trypanosome prevalence patterns in cattle, with peaks occurring either in May/June/July or November/December. The peaks of trypanosome prevalence therefore occurred either 4 months before or after the times of peak challenge from G. morsitans, not 1 or 2 months after as predicted by analytical models. In G. palpalis-infested areas there was little seasonal variation in abundance or trypanosome infections, but peak trypanosome prevalence still occurred mostly in June/July. Despite the incongruity between the months of peak prevalence and challenge, the overall annual prevalence rates and tsetse challenge indices showed a significant linear relationship. It is concluded that existing analytical models need to be refined to take into account trypanotolerance and the various influences on the expression of this trait.
The RFLP analysis of the β-tubulin gene region in New World Leishmania
Authors: Mendoza-León A. , Havercroft J. C. , Barker D. C.
Published: June 2009

We have examined the similarities and differences in the organization of tubulin genes in New World Leishmania by restriction endonuclease digestion of genomic DNA and Southern blot analysis, using heterologous and homologous tubulin gene probes. As judged by the hybridization pattern and the restriction fragment length polymorphism (RFLP), there were large differences in both the restriction and hybridization patterns of the β-tubulin sequences between stocks of the mexicana and braziliensis complexes. There were similarities in the hybridization patterns of different speciesof the mexicana complex. In contrast, a high heterogeneity was found between species of the braziliensis complex which includes intraspecific variation. The results suggest that this polymorphism may be associated with random mutations. The same analysis gave evidence of large differences in the β-tubulin gene restriction pattern between New and Old World Leishmania. This variation in the β-tubulin gene region was sufficient to distinguish between New and Old World Leishmania groups and between stocks of the mexicana and braziliensis complexes.
Differentiation of isolates in the genus Steinernema (Nematoda: Steinernematidae).by random amplified polymorphic DNA fragments and morphological characters
Authors: Liu J. , Berry R. E.
Published: June 2009

We combined polymerase chain reaction (PCR) amplification of DNA sequences and important morphological characters as a technique to differentiate nematode isolates in the genus Steinernema. Five decamer oligonucleotide primers were used to generate random amplified polymorphic DNA (RAPD) fragments from 11 nematode isolates. The primers generated 8–12 fragments, ranging from 220 to 1300 bp in size. Reproducible amplified DNA fragments of 11 isolates showed obviously inter- or intra-specific polymorphisms, enabling us to differentiate easily the nematode species and isolates. Combining RAPD–PCR fragments with the examination of morphological characters of infective juveniles and 1st-generation males, we identified isolate OH1S, collected from Newport, Oregon, as S.feltiae; isolate OS21, collected from Grants Pass, Oregon, belonged to a previously undescribed species. Our study may provide a rapid and reliable method for the identification of Steinernema nematodes.
Progarnia archosauriaenov. gen., nov. sp. (Haemosporina: Garniidae), a blood parasite ofCaiman crocodilus crocodilus(Archosauria: Crocodilia), and comments on the evolution of reptilian and avian haemosporines
Authors: Lainson R.
Published: June 2009

Progarnia archosauriaenov. gen., nov. sp. (Haemosporina: Garniidae) is described in the blood of the South American caiman,Caiman crocodilus crocodilus(Archosauria: Crocodilia). The parasite undergoes merogony and gametogony principally in leucocytes and thrombocytes, but also invades erythrocytes in which it produces no ‘malarial’ pigment. It thus shares features ofFallisiaandGarniawhich are, respectively, intra-leucocytic and intra-erythrocytic haemosporines of the family Garniidae in present-day lizards. This, and the antiquity of the order Crocodilia, suggests that it was from such a parasite that the existing reptilian and avian haemosporines evolved. An overall evolutionary pattern is suggested.
Initiation of chemical studies on the immunoreactive glycolipids of adultAscaris suum
Authors: Dennis R. D. , Baumeister S. , Smuda C. , Lochnit C. , Waider T. , Geyer E.
Published: June 2009

There is a general lack of basic information concerning one class of glycoconjugate, the glycolipids, from parasitic nematodes. As the prototype, the neutral glycolipid fraction derived from adult males ofAscaris suumwas investigated as to its chromatographic, differential chemical staining, antigenic and chemical properties. The thin-layer chromato-graphy-resolved neutral fraction glycolipids could be classified into components of fast and slow migrating band groups. Immunoreactivity was restricted to the latter as detected by IgG and IgM anti-neutral fraction glycolipid antibody levels in serial infection sera of mice. Similarities of chromatography, antigenicity and serological cross-reactivity have been extended to the neutral glycolipid fractions of other parasitic nematodes:Litomosoides cariniiandNippostrongylus brasiliensis. Chemical, differential chemical staining and enzymatic analyses identified theAscaris suumantigenic, slow migrating band group of components as amphoteric glycosphingolipids, and not the originally hypothesized glyco-glycerolipids or glycosylphosphatidylinositols, that contained typical neutral monosaccharide constituents and a zwitter-ionic phosphodiester linkage, most probably phosphocholine. Glycosphingolipid-immunoreactivity is eliminated on cleavage of the zwitterionic phosphodiester linkage by hydrofluoric acid treatment.
Further studies of cyclical transmission and antigenic variation of the ILDar 1 serodeme ofTrypanosoma vivax
Authors: Gardiner P. R. , Thatthi R. , Gathuo H. , Nelson R. , Moloo S. K.
Published: June 2009

Antigenic variation in the ILDar 1 serodeme of the naturally rodent-infective stock of West AfricanTrypanosoma vivaxhas been investigated following cyclical transmission. The immunofluorescent and immune lysis tests were employed with a panel of 39 variant-specific mouse antisera. When antigenically homogeneous, or mixed, populations were transmitted by tsetse flies to goats, the first peak parasitaemias arising in the goats were antigenic mixtures (up to 9 major, and several minor variants being recognized in some cases) from which the ingested variant was absent. Although first peak parasitaemias in similarly infected goats showed some variants in common, there was no obvious relationship between the VAT profiles in different goats. When these populations were expanded in irradiated mice, VAT heterogeneity was maintained with a tendency towards the development of predominant variants in some, but not all, instances. Six additional variants, derived following the growth of bloodstream form ILDat 1·9 in 37°C culture, were also represented in goat and mouse populations. Two further variants, isolated after cyclical development of ILDat 1·9-derived trypanosomesin vitro, were not present in the early parasitaemias in goats and mice.
Feeding behaviour of pathogen-infected vectors
Authors: Molyneux D. H. , Jefferies D.
Published: June 2009

Evidence from many sources indicates that, in several parasite–vector systems, flight ability, fecundity or gonotrophic concordance of vectors, are affected by parasites (including bacteria, rickettsia and viruses) and in some cases parasites cause well-documented pathogenic effects (see reviews, for example, by Lavoipierre (1958a) and Hawking & Worms (1961) on filaria; Molyneux (1977, 1983) for trypanosomatids; Killick-Kendrick (1979) for Leishmania).
A female-specific cDNA sequence ofSchistosoma mansoniencoding a mucin-like protein that is expressed in the epithelial cells of the reproductive duct
Authors: Menrath M. , Michel A. , Kunz W.
Published: June 2009

Seven cDN A clones ofSchistosoma mansonicontaining the C-terminal part of the deduced sequence of a mucin-like protein have been identified. The protein contains 28% threonines, 20% serines, and has a pi of 3middot;4. On Northern blots of RNA of adult worms, the cDNA clones detect 2 transcripts of 1middot;65 and 4middot;2 kb which are expressed only in female worms. The tissue of gene expression, as revealed byin situhybridization, is the epithelium surrounding the female reproduction duct proximal to its entrance into the ootype. Accumulation of N-glycosylation sites suggests that the protein, like other mucins, might form a protective layer, coating the lining of the duct. Regarding its acidic pi, we hypothesize a role in preventing premature egg-shell formation. This is the first female-specifically transcribed sequence, hitherto known inS.mansonithat is not expressed in the vitellaria.
The FMRFamide-like neuropeptide AF2 is present in the parasitic nematode Haemonchus contortus
Authors: Keating C. D. , Holden-Dye L. , Thorndyke M. C. , Williams R. G. , Mallett A. , Walker R. J.
Published: June 2009

Peptides belonging to the FMRFamide family are widely distributed amongst invertebrates. We report here on the isolation of the FMRFamide neuropeptide AF2 (Lys-His-Glu-Tyr-Leu-Arg-Phe-NH2) from the parasitic nematode Haemonchus contortus. Immunocytochemical techniques showed that FMRFamide-like material was distributed in several regions of these organisms including nerve cords and cell bodies of the central nervous system. AF2 was isolated using a method that employed 6 steps of reverse-phase HPLC. The concentration of AF2 in this organism was approximately 30 pmol/g of nematode.
Immunohistochemical and ultrastructural localization ofSchistosoma mansonisoluble egg antigens processed by the infected host
Authors: Bogers J. J. P. M. , Nibbeling H. A. M. , Deelder A. M. , Van Marck E. A. E.
Published: June 2009

The detection of egg-derived antigens in the serum and urine ofSchistosoma mansoni-infected individuals and experimental animals would provide an alternative method to assess the tissue egg burden. The detected levels are, however, not only a function of the amounts of antigen produced, but also of the processing or clearance by the host. In the present study the immunolocalization pattern of antigens using 2 recently described monoclonal antibodies to repetitive carbohydrate epitopes ofS. mansonisoluble egg antigen (114–5B1–A and 114–4D12–A) in various organs of the host was investigated. In the liver strong immunoreactivity could be detected around the entrapped eggs and in egg-shells, as well as in Kupffer cells accumulating both antigen and schistosomal pigment. In the spleen, immunohistochemistry revealed antigen in the plasma as well as in secondary lysosomes of macrophages. Strong labelling was found in the vesicles of the eosinophilic granulocytes: indirect evidence perhaps for the presence of antigen–antibody complexes. In conclusion, the secreted egg antigens were sequestered in the reticulo-endothelial macrophages of the liver and the spleen as already partly described for worm-derived antigens. The presence of large quantities of antigenic material in the spleen could suggest an important role of this organ in the clearance of antigen and might even provide an additional explanation for the hepatosplenomegaly mainly present inS. mansoni-infected children.
Measuring aggregation of parasites at different host population levels
Authors: Boulinier T. , Ives A. R. , Danchin E.
Published: June 2009

Parasites are generally found aggregated among hosts. In this paper we propose a method for measuring aggregation at different scales in the host population. We use the method to characterize the pattern of aggregation of the tickIxodes uriaeon chicks of its seabird host, the KittiwakeRissa tridactyla. We found evidence of aggregation at the among-nest scale, but not among chicks within nests. This shows that the processes leading to aggregation occur at a higher scale than the nest. The methods we develop provide a way to compare parasite aggregation at different scales in a quantitative fashion and can be applied in a large number of epidemiological studies.
Distribution and biophysical properties of fluorescent lipids on the surface of adultSchistosoma mansoni
Authors: Redman C. A. , Kusel J. R.
Published: June 2009

The properties of 4 fluorescent lipid compounds in the surface membrane of adult maleSchistosoma mansoniworms were examined by fluorescent microscopy and fluorescent recovery after photobleaching (FRAP). The data suggest that the probes N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl) sphingosine (BODIPY FL ceramide) and PKH2 pass through the outer membrane and enter structures in or below the membrane. In contrast 5-(N-octadecanoyl)aminofluorescein (AF18) and N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl) sphingosylphosphocholine (BODIPY FL sphingomyelin) insert into the outer monolayer. The DLvalues of these latter 2 compounds, 8·83 ± 2·35 × 10−9cm2s−1and 2·76 ± 0·53 × 10−9cm2s−1, respectively, suggest that they enter different domains. Furthermore, it was observed that both BODIPY FL ceramide and BODIPY FL sphingomyelin entered particular structures in or under the surface membrane. The possible nature of these particles is discussed.
Direct sequencing of the PCR amplified SSU rRNA gene ofEntamoeba disparand the design of primers for rapid differentiation fromEntamoeba histolytica
Authors: Novati S. , Sironi M. , Granata S. , Bruno A. , Gatti S. , Scaglia M. , Bandi C.
Published: June 2009

Since 1993, strains ofEntamoeba histolytica sensn latohave been assigned to 2 species on the basis of clinical, biochemical, immunological and genetic evidence: the pathogenic strains toE. histolytica sensu stricto, the non-pathogenic strains toEntamoeba dispar. Analysis of the gene encoding for the small subunit ribosomal RNA (SSU rDNA) supports the existence of 2 species. However, while 3 whole SSU rDNA sequences are available in the data bases forE. histolytica, only a partial sequence has been published forE. dispar. Here we report a SSU rDNA sequence forE. dispar. Compared to those ofE. histolytica, this sequence shows 1·7 % nucleotide substitutions. On the basis of our rDNA data, 2 primers were designed to produce polymerase chain reaction (PCR) amplification from bothE. histolytica and E. dispar. Primer specificity for the 2 amoebae was assessed both theoretically against the data bases, and experimentally against a collection of eukaryotic and prokaryotic DNAs. The amplified stretch encompasses a polymorphicDdeI restriction site which allows, after cleavage of the fragment,E. histolyticaandE. disparto be distinguished. The reliability of this method of identification was assessed comparing the results with those based on classic isoenzyme analysis.
Karyotype variability in Trypanosoma rangeli
Authors: Henriksson J. , Solari A. , Rydåker M. , Sousa O. E. , Pettersson U.
Published: June 2009

The molecular karyotypes of several different protozoan parasites show high intra-species variation, including different kinetoplastids such as Trypanosoma brucei, Trypanosoma cruzi and Leishmania ssp. In this study, the molecular karyotype of Trypanosoma rangeli was examined. To evaluate potential intra-species molecular karyotype variations, 16 different samples were studied by pulsed field gel electrophoresis (PFGE) followed by ethidium bromide staining and hybridizations with 6 different probes. The result showed that different T. rangeli populations are highly polymorphic regarding the molecular karyotype, and thus suggests that PFGE analysis can be used for classification of different T. rangeli isolates. In addition, the molecular karyotype of T. rangeli was compared to molecular karyotypes of other kinetoplastids, and was shown to be distinctly different from that of T. cruzi, but shows some similarities with the karyotype described for T. brucei. Among the probes used one was identified as highly polymorphic, and thus informative for studies of different T. rangeli populations, and another was useful for differentiation between T. rangeli and T. cruzi.
Surface antigens ofToxoplasma gondii
Authors: Couvreur G. , Sadak A. , Fortier B. , Dubremetz J. F.
Published: June 2009

Monoclonal antibodies reacting with pellicular antigens ofToxoplasma gondiitachyzoites have been selected among hybridomas produced against this organism by immunofluorescence assay. These antigens have been further characterized by immunofluorescence on living zoites, Western immunoblotting and immunoprecipitation of lactoperoxidase surface radio-iodinated tachyzoite lysates. The simultaneous characterization of 5 different surface antigens (P43, P35, P30, P23, P22) some of which have already been studied individually allowed a better definition of these antigens and the characterization of a yet undescribed surface molecule (P23).
Schizotrypanum in British bats
Authors: Gardner R. A. , Molyneux D. H.
Published: June 2009

Two species of Schizotrypanum, T. (S.) dionisii and T. (S.) vespertilionis, were identified from British bats. Laboratory studies on stocks of isolated trypanosomes from 5 species of bat (Pipistrellus pipistrellus, Nyctalus leisleri, N. noctula, Eptesicus serotinus and Myotis brandti) indicated that the predominant species was T. d. dionisii. Collections and dissection of the bat bug Cimex pipistrelli from bat roosts revealed flagellate infection in a total of 12 out of 20 bugs; 7 of these bugs had metacyclic trypanosomes present. C. pipistrelli and the human bed bug, C. lectularius were reared in the laboratory and allowed to feed on wild-caught bats known to be infected with T. d. dionisii. Development occurred in both species of Cimex. Cimex spp. could be used to detect subpatent Schizotrypanum infections by xenodiagnosis. This technique was used to test the parasitological status of bats collected in the wild or reared in captivity. On a single occasion an apparent transmission of T. d. dionisii to an uninfected (by xenodiagnosis) laboratory reared bat was achieved. A stock of Schizotrypanum isolated from a wild-caught C. pipistrelli collected in a N. leisteri roost was identified by DNA buoyant density centrifugation as T. (S.) vespertilionis. A P. pipistrellus known to be infected with T. d. dionisii was found to have cyst-like structures in thoracic skeletal muscle containing amastigotes. The study provided the strongest evidence yet that C. pipistrelli is the vector of Schizotrypanum in British bats.
DNA base composition of filarial nematodes
Authors: Rothstein N. , Stoller T. J. , Rajan T. V.
Published: June 2009

We have determined the molar content of guanine + cytosine (GC content) of DNA of the filarial nematode (Brugia malayi, Brugia pahangi and Dirofilaria imitis) and of the free-living soil nematodes Caenorhabditis elegans and have analysed the DNA for the presence of methylcytosine. Two independent methods, thermal denaturation and direct analysis of base content by HPLC following enzymatic hydrolysis, reveal that the GC content of filarial nematodes is 26–28%. We have been unable to find methylcytosine in the DNA of B. malayi.
Immunocytochemical demonstration of a neuropeptide in Ascaris suum (Nematoda) using an antiserum to FMR Famide
Authors: Davenport T. R. B. , Lee D. L. , Isaac R. E.
Published: June 2009

A FMRFamide-like peptide has been detected in the nematode Ascaris suum, using the peroxidase-anti-peroxidase (PAP) immunocytochemical technique. Positive reactions were obtained in both the central nervous system and the peripheral nervous system of the worm, the strongest reactions being in the anterior nerve ring, the cephalic papillary ganglia, the lateral ganglia and the dorso-rectal ganglion. Immunoreactivity was observed along the length of the main nerve cords of the worm and, to a lesser extent, in the pharyngeal nerve cords. The possible role of this neuropeptide in the physiology of the nematode is discussed.
Immune evasion bySchistosoma mansoni: loss of susceptibility to antibody or complement-dependent eosinophil attack by schistosomula cultured in medium free of macromolecules
Authors: Dessein A. , Samuelson J. C. , Butterworth A. E. , Hogan Maureen , Sherry Barbara A. , Vadas M. A. , David J. R.
Published: June 2009

Schistosomula ofSchistosoma mansoni, recovered either after penetration of cercariae through isolated rat skin or by mechanical transformation of cercariae, become fully resistant after 24–48 h of culture to damage by human blood eosinophils in the presence of human anti-schistosomular sera. Cultured schistosomula are also shown to lose their susceptibility to attack by human eosinophils in the presence of human complement. This resistance is related to the simultaneous reduction of the ability of human anti-schistosomular antibodies and human complement component C3 to bind to the surface of the cultured larvae. The development of insusceptibility to antibody, complement and eosinophil-mediated attack does not require the acquisition by the schistosomula of a protective coat of host or other macromolecules, since it is achieved in chemically defined culture medium free of serum and macromolecules. This supports the hypothesis that schistosomula undergo intrinsic changes which render them insusceptible to immune attack.
The effects of vector control on the antibody response to antigens ofOnchocerca volvulus
Authors: Bradley J. E. , Gillespie A. J. , Trenholme K. R. , Karam M.
Published: June 2009

The effects of exposure to infective larvae on the antibody response to a cocktail of specific recombinant antigens ofOnchocerca volvulusand to a worm extract were evaluated by comparing the responses of individuals from a vector controlled area with those from an area of continuing transmission by ELISA. Individuals from the vector controlled areas were found to have reduced responses to both antigen preparations. Amicrofilerdermic (mf–) individuals from the area of vector control exhibited significantly lower total and subclass IgG responses to the worm extract. In contrast, the responses to the cocktail of specific recombinants were significantly reduced in individuals from the area of vector control who were still microfilerdermia positive (mf+). The distribution of IgG subclass specific responses was similar to both antigen preparations, both dominated by the IgG4 and IgG1 subclasses. IgG1 responses to the worm extract remained elevated in the vector controlled individuals but IgG4 was significantly reduced in the mf – individuals. Both subclasses reflected the total IgG response to the cocktail of recombinants and were significantly reduced in individuals from the vector controlled area, when compared to individuals from the hyperendemic area. IgG1 responses to the cocktail of recombinants are significantly lower than IgG4 in all individuals and virtually absent in individuals from the vector-controlled area. Measuring total IgG and IgG4 is more sensitive than IgG1 in detecting infection, 100 or 97% respectively, but they remain elevated in the individuals from the vector controlled areas even after 8–10 years interruption of transmission. These results have important implications for the serological monitoring of control programmes in individuals who have previously been infected.