bluuebunny/crossref_metadata_2025 huggingface dataset:
Potential interactions between Acanthocephalus anguillae and Pomphorhynchus laevis in their natural hosts chub, Leuciscus cephalus and the European eel, Anguilla anguilla
Authors: Bates R. M. , Kennedy C. R.
Published: June 2009

Chub and eels were experimentally infected via intermediate hosts harbouring cystacanths, with Pomphorhynchus laevis alone, or Acanthocephalus anguillae alone, or simultaneously with mixtures of both species in varying proportions, and sampled at 7, 56 or 112 days post-infection. Examination of chub revealed that both species showed low establishment and growth rates, differing markedly from British field data, where chub is apparently one of the most important hosts, and preventing further meaningful experiments. Both species showed higher establishment rates in eels, but A. anguillae both grew faster and matured to a greater extent than P. laevis, reflecting field data. No evidence of any interactions, competitive or otherwise, was found in the mixed infections in eels at low or high infection levels. The results were interpretated with regard to British field data and current theories of the role of interspecific competition in structuring fish helminth communities.
Characterization of the relationships in the pinewood nematode species complex (PWNSC) (Bursaphelenchus spp.) using a heterologous unc-22 DNA probe from Caenorhabditis elegans
Authors: Abad P. , Tares S. , Brugier N. , De Guiran G.
Published: June 2009

Pine wilt is the most serious disease of native pines in Japan and potentially the most important nematode disease of conifers in the world. The pinewood nematode Bursaphelenchus xylophilus was found to be the causal agent. Difficulties arose with respect to the precise identity of some isolates of B. xylophilus and of similar species B. mucronatus and B. fraudulentus. Restriction enzyme analyses of repetitive DNA revealed bands specific for the species B. xylophilus, B. mucronatus and B. fraudulentus. Hybridization patterns obtained with unc-22 gene of C. elegans, clearly identified B. xylophilus, B. mucronatus and B. fraudulentus as well as the different geographic isolates of these species. Furthermore, it is possible to define the phylogenetic relationships between the different populations constituting the ‘pine wood nematode’ complex.
Experimental studies on the life-cycle ofRaillietiella gigliolii(Pentastomida: Cephalobaenida) in the South American worm-lizardAmphisbaena alba: a unique interaction involving two insects
Authors: Winch Judith M. , Riley J.
Published: June 2009

Raillietiella giglioliiis a cephalobaenid pentastomid which inhabits the lungs of the South American worm-lizardAmphisbaena alba. The host is a facultative inquiline of nests of the leaf-cutting antAtta cephaloteswhere it feeds occasionally (and possibly by accident) on ants but more often on beetles and their larvae which are themselves inquilines of ant nests. Ants store exhausted leaf-substrate in special underground chambers which serve as refuse dumps and it is here that larvae of the three-horned rhinoceros beetleCoetosis bilobafeed: these larvae are also known to be prey items ofA. alba. From observations of captive colonies ofAtta, we have demonstrated that pentastomid-egg contaminated faeces ofA. alba, introduced into the colony, are rapidly cut up and thrown onto the refuse dump, where, under natural circumstances they will be eaten byCoelosis. These larvae have an unusual and highly specialized gut physiology and parasite eggs will develop to an infective stage within the haemocoel in 70–96 days. Cockroaches are refractory to infection. Ants are the vital link in transmission since they literally deliver eggs to theCoelosislarvae. The strong trophic links which exist between the various components of the life-cycle offset a low fecundity of 100 eggs/female parasite/day but nonetheless maintain a high prevalence (86%) of infection.
Profilicollis botulus (Acanthocephala) abundance in the eider duck (Somateria mollissima) on the Ythan estuary, Aberdeenshire
Authors: Thompson A. B.
Published: June 2009

The abundance of Profilicollis botulus was monitored in eider ducks for 3 years. No significant difference in P. botulus abundance was found between eiders taken alive and those collected dead from the shore line, or between adult males and adult females. Adult male eiders had a seasonal pattern of infection. Incubating female eiders lost their infection in almost all cases, suggesting that a seasonal pattern of infection must also occur in these birds. Eiders in their first winter had P. botulus abundances which were approximately 10 times that of adult eiders, but by the following summer the abundance had declined to that found in adults. Data are compared with previous studies undertaken on the Ythan estuary. Captive eiders were used to determine the developmental rate of female P. botulus and the percentage of administered cystacanths which established in the intestine. There was no evidence to suggest that male and female P. botulus have different life–spans.
Differential cellular responses atHyalomma anatolicum anatolicumfeeding sites on susceptible and tick–resistant rabbits
Authors: Gill H. S. , Walker A. R.
Published: June 2009

The sequential, quantitative histological analysis of adultHyalomma anatolicum anatolicumfeeding sites on rabbits showed that the cellular reactions at tick feeding sites change in character and magnitude with time after attachment, and differ considerably from primary infestation to tertiary infestation. Neutrophils (62–68%) followed by mononuclear cells (22–24%) were the major component of the cellular infiltrate throughout primary infestation. Eosinophils accounted for 10% of the cellular infiltrate at 24 h after attachment. Their proportions declined thereafter, forming 9% of the infiltrate at 72 h and 5% at 144 h. Basophil infiltration in most of the feeding lesions was noticed by 24 h, but always in low numbers. Despite a slight increase in absolute numbers the proportion of basophils fell from 3% at 24 h to 2– at 144 h. In contrast to primary infestation the cellular reactions on tertiary infestations were characterized by a significant increase in the numbers of basophils and eosinophils and marked degranulation of mast cells and basophils as early as 24 h after attachment. As the feeding advanced there was an increase in the mean proportions of basophils from 4% to 9% and mononuclear cells from 22% to 38%, and a decrease in the proportion of eosinophils from 21% to 9%. However, neutrophils (42–53%) remained the major component of the cellular infiltrate. There was no significant difference in the nature and sequence of cellular events in the feeding sites of male and female ticks, although the lesions produced by feeding males were 5–10 fold smaller than those of females. Mast cells, basophils and eosinophils appeared to be the major host cells involved in the resistance response, manifested by protracted feeding, reduced engorgement weight and poor egg laying. The mechanisms by which these cells might interact to mediate resistance are suggested and discussed.
Investigations into natural and experimental infections of freshwater fish by the common eye-fluke Diplostomum spathaceum Rud.
Authors: Sweeting R. A.
Published: June 2009

The range of fish hosts parasitized by Diplostomum spathaceum was assessed. Natural and experimental levels of infection were compared between host species. The accumulation of eye flukes with age was established in one host – Rutilus rutilus. Development of metacarcariae in lenses of naturally infected Gasterosteus aculeatus throughout the year was compared with that of experimentally infected South African clawed toads, Xenopus laevis, maintained at various temperatures (5–30 °C). The importance of temperature changes to this part of the life-cycle of the parasite is discussed.
The population dynamics of Lepeophtheirus pectoralis (Müller): dispersion pattern
Authors: Boxshall G. A.
Published: June 2009

The numerical relationships between a population of Lepeophtheirus pectoralis and its host population (plaice) have been described. There was no significant difference between infection levels in male and female plaice. In most of the monthly samples (75%) there was no significant relationship between host length and either the incidence or intensity of infection. The samples in which significant positive correlations occurred were usually taken within the period November to April. It is probable that the immigration of smaller fish, with lower levels of infection, from shallower water produces this effect.

The parasite population was found to have an overdispersed distribution (variance > mean) within its habitat, the host population. The frequency distributions of numbers of parasites per fish were calculated and the negative binomial distribution was fitted to these. The fit was good in 22 of the 24 samples and the value of k, the exponent, was found to be directly related to the mean density of the parasite population. Iwao's (1970) method of dispersion analysis indicated that the observed negative binomial was generated by a model of randomly distributed clumps or colonies of individuals. A possible mechanism of producing this pattern was proposed based on evidence from studies of mortality in the parasite population (which indicated that all-or-none type mortality operates on the clumps at certain periods during the year), the infection process (which demonstrated that a single wave of infection produces an overdispersed spatial distribution) and the examination of parasites from individual fish (which displayed a clumping of parasites at certain stages rather than an even spread over the range of possible stages). The mechanism proposed is that the adaptations for host location of the infective copepodid stage tend to produce aggregations of these larvae in favourable areas of a heterogeneous habitat. Fish moving randomly into these areas will tend to be infected by more than one larva (a clump of larvae) at any one time when available for infection. The fish can be regarded as equivalent to random samples of the free larval population and the aggregated distribution of the parasite population on its hosts is therefore directly related to the aggregated distribution of the free-swimming infective larvae.
Population dynamics ofHymenolepis nanain mice: fecundity and the ‘crowding effect’
Authors: Ghazal A. M. , Avery R. A.
Published: June 2009

Young white mice were infected with different doses of eggs or cysticercoids ofHymenolepis nanaand the subsequent faecal egg output was measured over a 3-day period. This was then correlated with worm numbers, determined after killing the hosts. The longest worm in each infection was measured and it was shown that crowding decreased the linear dimensions, number of eggs per proglottis and rate of proglottis production of these worms, but that their shape was not affected.

The relation between total egg output and worm numbers was complex. In both egg-derived and cysticercoid-derived infections the egg production rose to a peak, fell and then levelled off to a constant rate with increasing worm numbers. Cysticercoid-derived worms were larger than egg-derived worms, but produced approximately the same number of eggs per unit of biomass. The differences in the egg output curves for the two types of infection were interpreted as being due to their size difference; this in turn may be a consequence of the host immunological response.
Studies on intrategumental pH and its regulation in adult male Schistosoma mansoni
Authors: Pax R. A. , Bennett J. L.
Published: June 2009

The intrategumental pH in adult male Schistosoma mansoni as measured with pH-sensitive microelectrodes is between 7.0 and 7.2, a value about one pH unit more alkaline than expected for equilibrium. This value is maintained for at least 4 h after isolation in media buffered with Hepes or CO2/ with or without serum present. CCCP (1 μM) and FCCP (10 μM) cause rapid acidification. DNP (1 mM) and Na-orthovanadate (1 mM) acidify but also cause significant depolarization of the tegument. NH (20 mM) depolarizes and acidifies the tegument with no evidence of transient alkalinization. High K+ (25 mM) accelerates the acidification. Removal of the NH+4 causes a large transient further acidification with recovery requiring as long as 40 min. High K+ (25 mM) delays the early stage of the recovery. Presence of CO2/HCO in the incubation medium does not accelerate the recovery rate nor does SITS (100 μM) inhibit the recovery. Intrategumental Na+ is elevated after an acid load and amiloride (3 mM) as well as low Na+ medium interfere with recovery from the acid load indicating that a Na+–H+ exchanger may be present in the tegumental membrane.
Avermectin and avermectin derivatives are antagonists at the 4-aminobutyric acid (GABA) receptor on the somatic muscle cells ofAscaris; is this the site of anthelmintic action?
Authors: Dye-Holden L. , Walker R. J.
Published: June 2009

The mechanism underlying the ability of the anthelmintic avermectin to paralyse the nematodeAscarisis not yet fully understood. Using conventional two-electrode electrophysiological recording techniques we have demonstrated that micromolar concentrations of ivermectin block the inhibitory GABA response on the muscle cells of the parasitic nematodeAscaris. The ability of a number of avermectin derivatives to act as receptor antagonists for theAscarismuscle GABA receptor has been determined. This provides useful information to compare with thein vivoanthelmintic potency of these compounds. Abamectin, the most potent anthelmintic, was the most potent compound at inhibiting the GABA response whilst octahydroavermectin, a compound which lacks anthelmintic activity, did not block the GABA receptor. This is consistent with the notion that the GABA receptor antagonist properties of the avermectins could contribute to their anthelmintic action.
Genetic diversity and genetic differentiation inEchinococcus granulosus(Batsch, 1786) from domestic and sylvatic hosts on the mainland of Australia
Authors: Lymbery A. J. , Thompson R. C. A. , Hobbs R. P.
Published: June 2009

Enzyme electrophoresis was used to examine genetic variation within and between populations ofEchinococcus granulosusfrom domestic and sylvatic hosts in western and eastern Australia. Substantial genetic diversity was found within all populations. There was no evidence, however, of genetic differentiation between populations from different hosts or geographic areas. When isolates were grouped into previously described domestic or sylvatic strains on the basis of rostellar hook morphology, most (94%) of the genetic variation occurred within, rather than between strains. These results conflict with the currently accepted theory of separate domestic and sylvatic strains ofE. granulosuson the mainland of Australia.
MetacyclicTrypanosoma vivaxpossess a surface coat
Authors: Gardiner P. R , Webster P , Jenni L , Moloo S. K
Published: June 2009

Coated metacyclics ofTrypanosoma vivaxexist in the hypopharynges of infected tsetse flies and are extruded in low numbers when the flies are induced to probe onto warm slides or into medium. After extensive searching ofT. vivax-infected proboscides, and resort to a process for the examination of single, extruded, metacyclic trypanosomes, electron micro scopic evidence is presented that, contrary to an earlier report, metacyclicT. vivaxacquire a surface coat before contact with the mammalian host. SinceT. vivaxexhibits antigenic variation, the role of the surface coat in this species is likely to be functionally equivalent to the surface coat of the other tsetse-transmitted trypanosome species,T. bruceiandT. congolense.
Speciation and specificity of acanthocephalans. Genetic and morphological studies of Acanthocephaloides geneticus sp. nov. parasitizing Arnoglossus laterna (Bothidae) from the Mediterranean littoral (Sète-France)
Authors: Buron I. De , Renaud F. , Euzet L.
Published: June 2009

Acanthocephaloides geneticus sp.nov. is described from Arnoglossus laterna (Bothidae) from the Mediterranean littoral (Sète-France). The new species most closely resembles Acanthocephaloides propinquus (Dujardin, 1845) Meyer, 1932, whose type host is Gobius niger (Gobiidae). A genetic comparison of the parasites collected from these two Teleostean fishes has confirmed the value of morphological differences which seemed too slight to raise the populations to species status.
A further model for temporal patterns in the epidemiology of schistosome infections of snails
Authors: Woolhouse M. E. J. , Chandiwana S. K.
Published: June 2009

The prevalence ofSchistosoma mansoniinfections ofBiomphalaria pfeifferishows seasonal variation. Field data from Zimbabwe show annual ranges from 0 to 7%. In this paper a mathematical model ofB. pfeifferipopulation dynamics andS. mansoniepidemiology is used as a framework for analysis of these patterns. Snail fecundity is a function of snail age and of temperature, and is apparently affected by other seasonal factors. The pre-patent period is dependent on temperature. Infection affects snail fecundity and mortality. Parameter values are derived from previous field and laboratory studies. The force-of-infection is estimated from the analysis of size-prevalence data. Using observed temperatures, model output agrees well with field data on snail abundance and prevalence of infection over a 14-month period. Seasonal variation in prevalence largely reflects variation in the pre-patent period and in snail population age structure. The possible role of seasonality in the force-of-infection is discussed. Prevalence patterns are not greatly affected by year-to-year differences in temperature. Significant seasonal variation in snail–man transmission rates is expected.
The identification of biological species in the genus Heterorhabditis (Nematoda: Heterorhabditidae) by cross-breeding second-generation amphimictic adults
Authors: Dix I. , Burnell A. M. , Griffin C. T. , Joyce S. A. , Nugent M. J. , Downes M. J.
Published: June 2009

Entomopathogenic nematodes of the genus Heterorhabditis are morphologically conservative, consequently the majority of isolates remain unassigned at the species level. When a Heterorhabditis infective juvenile infects an insect host, it develops into a protandrous hermaphrodite female. These first-generation females give rise to a second generation which contains both males and females. Because of this complex life-cycle and also because of uncertainty as to whether second-generation females are amphimictic, cross-breeding studies to facilitate species determination have not been carried out previously. We demonstrate here that second-generation Heterorhabditis females are amphimictic. Because of this finding, we have been able to develop a successful cross-breeding technique for the purposes of species determination in Heterorhabditis. Interstrain crosses using second-generation males and females from the appropriate strains have been successfully set up in Xenorhabdus luminescens-treated G. mellonella cadavers and also on agar plates. Using the techniques described here we confirm that H. bacteriophora (Brecon strain), H. megidis and H. zealandica are distinct biological species, we note that the H. bacteriophora group contains at least 2 species and we provide evidence for the existence of a new Irish species of Heterorhabditis.
Effects of cyclosporin A on the morphology and tegumentary ultrastructure of Hymenolepis microstoma in vivo
Authors: Wastling J. M. , Mackenzie K. , Chappell L. H.
Published: June 2009

Cyclosporin A (CsA) induced significant changes in parasite morphology when administered to mice infected with Hymenolepis microstoma. Gross morphological damage consisted of proglottis swelling and the formation of protuberances from the worm surface, visible with a low-power dissecting microscope, occurring most frequently in the posterior third of the strobila. Gross morphology and ultrastructure were examined further using scanning and transmission electron microscopy. Swollen proglottides exhibited areas covered in small pits and fissures (diameter approximately 1–2 μm) but it was not possible to establish the significance of this damage. The brush-border and distal cytoplasm appeared largely intact although some evidence of swelling of the basal membrane invaginations and possible fluid accumulation was seen in drug-treated TEM sections. The apparent oedematous condition of many of the proglottides from drug-treated mice may indicate that CsA treatment mediates permeability changes in the worm surface membrane but the mechanisms by which this may occur remain to be elucidated. The effects of CsA on the morphology of H. microstoma correlate with the previously described anthelmintic activity of the drug against this parasite where CsA treatment dramatically reduces worm growth, retards migration into the bile duct and limits parasite survival.
Host-parasite relationship between congenitalToxoplasmainfection and mouse brain: role of small vessels
Authors: Sims T. A. , Hay J.
Published: June 2009

Small vessels showing inflammatory cell infiltrates were invariably observed in the vicinity of intactToxoplasmatissue cysts within the brains of mice congenitally infected with the protozoan. Lymphocytes were observed in intimate contact with the luminal aspect of the endothelium, penetrating into the thickened basal lamina and in the perivascular area, which also contained macrophages and neutrophilic granulocytes. Rarely, lymphocytes were observed attached to the outer membrane of the host neurone which contained aToxoplasmatissue cyst and within the inflammatory infiltrate associated with a disintegrating cyst. An hypothesis is presented which combines these morphological observations to explain the events associated with tissue cyst associated recrudescence of latentToxoplasmainfection in mouse brain.
Immunocytochemical demonstration of a SALMFamide-like neuropeptide in the nervous system of adult and larval stages of the human blood fluke,Schistosoma mansoni
Authors: Brownlee D. J. A. , Fairweather I. , Johnston C. F. , Thorndyke M. C. , Skuce P. J.
Published: June 2009

The localization and distribution of SALMFamide immunoreactivity (IR), SI(GFNSALMFamide), in the nervous system of both the adult and larval stages of the trematodeSchistosoma mansonihas been determined by an indirect immunofluorescent technique in conjunction with confocal scanning laser microscopy (CSLM). Immunostaining was widespread in the nervous system of adult male and femaleS. mansoni. In the central nervous system (CNS), IR was evident in nerve cells and fibres in the anterior ganglia, cerebral commissure and dorsal and ventral nerve cords. In the peripheral nervous system (PNS), IR was apparent in nerve plexuses associated with the subtegmental musculature, oral and ventral suckers, the lining of the gynaecophoric canal, and in fine nerve fibres innervating the dorsal tubercles of the male worm. In the reproductive system of male and female worms, Sl-IR was only observed around the ootype/Mehlis' gland complex in the female. Immunostaining was also evident in the nervous system of both miracidium and cercarial larval stages. A post-embedding, IgG-conjugated colloidal gold immunostaining technique was employed to examine the subcellular distribution of SALMFamide-IR in the CNS ofS. mansoni. Gold labelling of peptide was localized over dense-cored vesicles within nerve cell bodies and fibres constituting the neuropile of the anterior ganglia, cerebral commissure and nerve cords of the CNS. Antigen pre-absorption studies indicated that the results obtained do suggest S1-like immunostaining and not cross-reactivity with other peptides, in particular FMRFamide.
Detection of host DNA sequences including the H-2 locus of the major histocompatibility complex in schistosomes
Authors: Iwamura Y. , Yonekawa H. , Irie Y.
Published: June 2009

The mouse type 2Alu(B2) sequence was detected in both DNAs ofSchistosoma mansoniandS. japonicumexcept for the cercarial stage by the polymerase chain reaction (PCR). Using several kinds of mouse STMS (sequence tagged microsatellite site) primer sets, PCR products related to the host were found in the DNAs ofS. mansonias well as ofS. japonicum. Products could be detected only in the DNA ofS. japonicumusing certain STMS primer sets. The fact that no products could be amplified from the DNAs of both parasites when other kinds of STMS primer sets were used suggests unequal incorporation of the host DNA into the schistosomes. Furthermore, the sequence of the N-terminal domain of H-2, the mouse major histocompatibility complex (MHC), was detected in the DNAs fromS. mansonimiracidium, male adult andS. japonicumadults, whereas the sequence of the C2domain of H-2 was found only in the DNAs ofS. japonicumadults. This evidence that host DNA sequences, including the class I MHC, exist heterogeneously in the DNAs of schistosomes might provide an important insight for further understanding of host-parasite immune interactions.
Study on the intramolluscal development of Schistosoma bovis: demonstration of three patterns of sporocystogenesis by daughter sporocysts
Authors: Touassem R. , Théron A.
Published: June 2009

Daughter sporocysts (SpII) of Schistosoma bovis produced by the mother sporocyst (SpI) can direct their production along three different pathways during intramolluscal development. (i) Direct sporocystogenesis–tertiary sporocysts (SpIII) are directly produced by non-cercariae producing daugher sporocysts (SpIII). (ii) Simultaneous sporocystogenesis and cercariogenesis–SpIII are produced by Spil in which cercariae are being produced. (iii) Sporocystogenesis after cercariogenesis-Spill are produced by SpIl in which cercariae are undergoing degeneration. These mechanisms can be interpreted in terms of demographic strategy leading swiftly to the taking over and optimum exploitation of the host's hiotic capacity.
Echinococcus granulosus infection in mice: host responses during primary and secondary infection
Authors: Riley E. M. , Dixon J. B. , Jenkins P. , Ross O.
Published: June 2009

The reaction of Balb/c mice to primary and secondary subcutaneous infection with chinoeoccu.s granulosus protoscoleces (PSC) is described. From 3 to 14 days following primary exposure to PSC, draining lymph nodes increase in weight and there is expansion of T and B lymphocyte populations, enhancement of in vitro lymphocyte transformational responses and production of PSC-specific 1gM and IgE antibodies. Despite the persistence of viable PSC in host tissues, lymphocyte responses decline to pre-infection values over the period 3–8 weeks post-infection. Secondary exposure to PSC immediately induces lympho proliferation, enhancement of transformational responses, production of IgE antibody and encapsulation of PSC by inflammatory cells. Although specific antibody levels remain high until at least 8 weeks after challenge infection, lymphocyte activity begins to decline after 4 days and is profoundly suppressed by 10 days. Parasite viability appears to be significantly reduced in secondary, as opposed to primary, infection and is associated with the accumulation of large numbers of eosinophils, mast cells and macrophages in infected tissues.
Environmental sex determination and density-dependent population regulation in the entomogenous nematodeRomanomermis culicivorax
Authors: Tingley G. A. , Anderson R. M.
Published: June 2009

Environmental sex determination in the mermithid nematodeRomanomermisculicivorax is examined in the context of parasite reproductive success and population regulation. Experimental results show that the sex ratio of the nematode within its mosquito host (Culex quinquefasciatus) is dependent on parasite density. Sex ratios are biased to females at low parasite burdens and to males at high parasite burdens. Low temperature further enhances female-biased ratios. The net effect of density-dependent sex determination on parasite and host population growth is shown to be critically dependent on the frequency distribution of parasite numbers/host. Mermithid parasite distributions within natural host populations show low degrees of aggregation relative to other helminth species. The population regulation of the parasite is examined with respect to environmental sex determination and parasite-induced host mortalities by means of simple mathematical models of the dynamics of parasite transmission via its life-cycle. The significance of regulatory constraints on population growth are discussed in relation to the use of mermithids as biological control agents of insect pests or disease vectors.
Cytoadherence of knobby and knoblessPlasmodium falciparum-infected erythrocytes
Authors: Ruangjirachuporn W. , Afzelius B. A. , Paulie S. , Wahlgren M. , Berzins K. , Perlmann P.
Published: June 2009

Cytoadherence ofPlasmodium falciparum-infected erythrocytes to melanoma cells was analysed using strains or isolates of parasites expressing or not expressing knobs (K+or K−phenotype) on the erythrocyte surface. Both K+and K−parasites had the capacity to cytoadhere to melanoma cells. Using a panel of melanoma cell lines with different surface expression of the cytoadherence receptors CD36, thrombospondin and ICAM-1 indicated that CD36 was the major receptor for parasites of both K+and K−phenotypes. Binding competition experiments between K+and K−-infected erythrocytes suggested that K+cytoadherence is of higher affinity than that of K−parasites. However, some K−cytoadherence was also found in isolates containing mixed populations of K+and K−parasites. The interaction of the two types of infected erythrocytes with melanoma cells also differed ultrastructurally, erythrocytes of K+phenotype showing intimate interdigitations with microvilli on the melanoma cells, while erythrocytes of K−phenotype displayed more separated interactions with fewer sites of contact and involving only a few melanoma cell microvilli. One and the same infected erythrocyte may co-express the ligand for CD36-mediated cytoadherence and the structures mediating binding of uninfected erythrocytes to form rosettes.
BloodstreamTrypanosoma cruziparasites from mice simultaneously express antigens that are markers of acute and chronic human Chagas disease
Authors: Leguizamon M. S. , Campetella O. E. , Reyes M. B. , Ibañez C. F. , Basombrio M. A. , Rincon J. , Örn A. , Frasch A. C. C.
Published: June 2009

Several recombinantTrypanosoma cruziproteins previously isolated were used as antigens to analyse antibody specificities present in sera from human infections. Some parasite proteins such as SAPA (Shed Acute Phase Antigen) are antigenic early after infection. Others, like antigens 1 and 30, are antigenic mainly during the chronic phase of the infection. To understand why different proteins are antigenic at different periods of infection, specificities of antibodies present in the sera of infected mice were compared with the antigens expressed by parasites collected directly from blood. Parasites collected during the acute parasitaemia peak expressed not only antigen SAPA, but also antigens 1 and 30. However, only antibodies against SAPA were frequently observed during the early period and also in the chronic phase of murine infection. Long-lasting antibodies against SAPA were detected regardless of the mouse and parasite strains used. Furthermore, all 8 recombinant clones detected in aT. cruziexpression library with pooled sera from acutely infected mice were homologous to the SAPA gene. These results show that even though parasites from the acute parasitaemia peak in mice may express simultaneously several proteins known to be antigenic, only antibodies against SAPA were consistently detected.
Division of Giardia isolates from humans into two genetically distinct assemblages by electrophoretic analysis of enzymes encoded at 27 loci and comparison with Giardia muris
Authors: Mayrhofer G. , Andrews R. H. , Ey P. L. , Chilton N. B.
Published: June 2009

Giardia that infect humans are known to be heterogeneous but they are assigned currently to a single species, Giardia intestinalis (syn. G. lamblia). The genetic differences that exist within G. intestinalis have not yet been assessed quantitatively and neither have they been compared in magnitude with those that exist between G. intestinalis and species that are morphologically similar (G. duodenalis) or morphologically distinct (e.g. G. muris). In this study, 60 Australian isolates of G. intestinalis were analysed electrophoretically at 27 enzyme loci and compared with G. muris and a feline isolate of G. duodenalis. Isolates of G. intestinalis were distinct genetically from both G. muris (approximately 80% fixed allelic differences) and the feline G. duodenalis isolate (approximately 75% fixed allelic differences). The G. intestinalis isolates were extremely heterogeneous but they fell into 2 major genetic assemblages, separated by fixed allelic differences at approximately 60% of loci examined. The magnitude of the genetic differences between the G. intestinalis assemblages approached the level that distinguished the G. duodenalis isolate from the morphologically distinct G. muris. This raises important questions about the evolutionary relationships of the assemblages with Homo sapiens, the possibility of ancient or contemporary transmission from animal hosts to humans and the biogeographical origins of the two clusters.
Variation in the vector competence of Aedes polynesiensis for Wuchereria bancrofti
Authors: Failloux A.-B. , Raymond M. , Ung A. , Glaziou P. , Martin P. M. V. , Pasteur N.
Published: June 2009

The vector competences of 6 geographic strains of Aedes polynesiensis for Wuchereria bancrofti were studied using two types of experimental infections. Experimental infection of laboratory-bred mosquitoes fed on the carriers' forearms with different levels of microfilaraemia showed that microfilariae (mf) uptake was directly proportional to the carrier's mf density and, as mf densities decreased, concentration capacity of Ae. polynesiensis increased. It was also shown that infection has an important effect on mosquito mortality, and that the mortality rate differed among mosquito strains. In infections using artificial feeders, the mf uptake was closely regulated, thus showing differences in the vectorial efficiency of Ae. polynesiensis related to the geographic origin of the mosquito strain. The mosquitoes from the Society archipelago were more efficient intermediate hosts than geographically distant strains when infected with W. bancrofti from an island within the archipelago (Tahiti). Mosquito strains from the Society archipelago developed the highest proportion of infective-stage larvae and exhibited the lowest mortality rate when infected with sympatric Tahitian W. bancrofti.
Cytokine and immunoglobulin subclass responses of rats to infection withEimeria nieschulzi
Authors: Smith N. C. , Ovington K. S. , Deplazes P. , Eckert J.
Published: June 2009

SIV rats infected with a high dose (50000 oocysts) ofEimeria nieschulzidisplayed clinical symptoms of coccidiosis such as diarrhoea (days 6 and 7 post-primary infection) and weight loss (days 6–8 post-primary infection) and were completely immune to challenge with a similar dose. The ability of rats to produce tumour necrosis factor (TNF)in vivowas enhanced during the period of oocyst excretion in the primary infection but significant production of TNF did not occur after challenge infection. Thus, TNF does not appear to be an important factor in resistance to infection withE. nieschulzibut may play some role in resistance to primary infection and in the pathology associated withE. nieschulziinfection. Parasite-specific serum IgM levels (measured by enzyme-linked immunosorbent assay) were also increased during primary infection but returned to background levels at the end of the patent period and were not affected by challenge infection. In contrast to TNF and IgM, serum concentrations ofE. nieschulzi-specific IgGl, IgG2a, IgG2b, IgG2c and intestinal tissue levels of IgA did not begin to increase until after day 12 post-primary infection, reached peak levels between days 20 and 30 post-primary infection and were slightly increased by challenge infection.
The temperature threshold for development of Elaphostrongylus rangiferi in the intermediate host: an adaptation to winter survival?
Authors: Schjetlein J. , Skorping A.
Published: June 2009

To test the hypothesis that the relatively high developmental temperature threshold of the parasitic nematode Elaphostrongylus rangiferi in the intermediate snail host is an adaptation to minimize larval mortality during winter, an experiment was set up in which snails of the species Arianta arbustorum were experimentally infected with the parasite. The snails were divided into 3 groups known to contain 1st, 2nd or 3rd-stage larvae, and incubated at 3 °C for an experimental period of 18 weeks. First-stage larvae showed a significantly higher survival rate within snails than 2nd or 3rd-stage larvae. We also found that snails carrying 1st-stage larvae survived better than snails with other larval stages. It is concluded that if the nematode has started development before the hibernation, this has a real and significant effect on the risk of dying. The high developmental threshold is therefore likely to be an adaptation to reduce the chance of hibernating as developing larvae during long periods of low temperatures.
Proterometra macrostoma(Digenea: Azygiidae): variations in cercarial morphology and physiology
Authors: Riley M. W. , Uglem G. L.
Published: June 2009

Snails,Elimia semicarinata, infected withProterometra macrostomawere collected monthly in 1990 and 1991 from North Elkhorn Creek near Lexington, Kentucky, and kept on a 12:12 h light–dark cycle for 2 weeks. Cercariae emerging from snails were classified into 8 strains (I–VIII) based on differences in number and distribution of spined and spineless papillae on the tail. Cercariae also had unique patterns of emergence, swimming behaviour and infectivity in 4 species of sunfish. Of 513 infected snails collected in May, 339 had pure infections with the strain frequencies (% of 339): I, 46·6; II, 7·7; III, 12·1; IV, 8·8; V, 0·6; VI, 2·7; VII, 11·8; VIII, 9·7. In the multiple infections, 159 snails shed 2 strains, 14 shed 3, and 1 snail shed 4 strains simultaneously. A comparison of sunfish and parasite populations in Kentucky, Ohio and Michigan indicated that strain frequency inP. macrostomais regulated by the species composition of the sunfish population.
The energetic consequences of parasitism: effects of a developing infection ofTrichostrongylus tenuis(Nematoda) on red grouse (Lagopus lagopus scoticus) energy balance, body weight and condition
Authors: Delahay R. J. , Speakman J. R. , Moss R.
Published: June 2009

The timing of the energetic consequences of a developing, single-dose infection ofTrichostrongylus tenuislarvae was investigated in captive red grouseLagopus lagopus scoticus. At 12 days post-infection (p.i.), infected birds had a resting metabolic rate 16% greater than controls and thenceforth lost weight at a faster rate than controls. At 16 days p.i. infected birds consumed 38% less energy and excreted 33% less energy than controls. The estimated total daily energy expenditure and energy expended on activity for infected birds at 16 days p.i. were 36% and 83% lower, respectively, than for controls. Infected birds lost condition from 16 days p.i. onwards. The period of energy imbalance at 12–16 days p.i. coincided with development of late 4th-stage larvae into adult worms and the onset of patency. After this, the effects on energy balance diminished. Synchronous development of previously arrestedT. tenuislarvae in wild birds in spring probably has similar effects to those reported here and places grouse under conditions of energy imbalance. The observed effects on energy balance provide a possible mechanism by which the parasite can reduce fecundity and survival of infected grouse.
Ecological, morphological and genetic characterization of sympatric Haemonchus spp. parasites of domestic ruminants in Mauritania
Authors: Jacquiet P. , Humbert J. F. , Comes A. M. , Cabaret J. , Thiam A. , Cheikh D.
Published: June 2009

The 4 species of ruminants (dromedary, zebu cattle, sheep and goat) in arid areas of Mauritania harboured Haemonchus spp. as the most frequent internal parasite. This was a rare situation where the 3 putative species, H. longistipes (dromedary), H. placet (zebu cattle) and H. contortus (sheep and goat) occurred sympatrically. The study was undertaken on hosts slaughtered at the Nouakchott abattoir, on the basis of monthly collection of worms. The environment was very unfavourable to H. placei and unfavourable to H. contortus, as intensity of infection remained low throughout the year, whereas infection in the dromedary was 10 to 20-fold higher. The survival strategies during the long, dry season were different: the surviving stages were either 4th-stage larvae in digesta (dromedaries), 4th-stage larvae either in digesta or mucosae (cattle), or 4th-stage larvae in mucosae and few adults (sheep and goats). The prolificacy of female worms, indicative of the potential to contaminate pastures, was similar for all Haemonchus spp. in the rainy season. H. longistipes behave differently during the pre-rainy season as no increase of prolificacy could be demonstrated as observed in the other species. Traits of vulvar morphology are considered as markers of ecological adaptation and were studied. The knobbed and smooth female morphs (in equal proportions) were the most frequent in H. longistipes, the knobbed morph out-numbered the other morphs in H. placei, and all 3 morphs were present in sheep and goats with the linguiform form being predominant. Genetic characterization of the 3 species was performed by means of Random Amplified Polymorphic DNA (RAPD). Three groups were obtained from analysis of these data: 1 group with individuals of H. contortus, 1 group with individuals of H. placei, and 1 group with individuals of H. longistipes. This indicated that, although the 3 species were valid, H. contortus and H. placei were more similar. Intraspecific variability was 2-fold higher in H. contortus than in the 2 other species. The ecological, morphological and genetical studies showed that H. longistipes, H. placei and H. contortus could be arranged in increasing order of variability.
Proteinases in the excretory/secretory products (ES) of adultTrichinella spiralis
Authors: Todorova V. K. , Knox D. P. , Kennedy M. W.
Published: June 2009

AdultTrichinella spiraliswere maintainedin vitrousing defined media and the material excreted/secreted (ES) during this time examined for proteolytic enzyme (proteinase) activity using an azocasein assay and gelatin-substrate gels. Several discrete proteinases in the size range 14–100 kDa were observed with optimal activity at pH 7·5. The use of a class-differentiating panel of proteinase inhibitors indicated that serine proteinases were predominant although some inhibition was evident in the presence of cysteine and metalloproteinase inhibitors. Of a panel of potential natural protein substrates tested, ES proteinases only degraded fibrinogen and plasminogen and degradation was, in part, susceptible to the action of serine, cysteine and aspartyl proteinase inhibitors. In addition, antibody harvested from immune but not normal mice inhibited ES proteinase activity, an observation of relevance to the immunobiology of Trichinosis.
Phylogenetic relationships between Toxoplasma and Sarcocystis deduced from a comparison of 18S rDNA sequences
Authors: Ellis J. T. , Luton K. , Baverstock P. R. , Whitworth G. , Tenter A. M. , Johnson A. M.
Published: June 2009

The current taxonomy of parasites in the genus Sarcocystis is largely based on morphological characteristics as well as on host specificity and life-cycle structure. Recently, phylogenetic analyses of partial ribosomal RNA (rRNA) sequences provided support for paraphyly of Sarcocystis. We have tested the validity of this hypothesis by sequencing the complete 18S rRNA genes of Sarcocystis arieticanis, Sarcocystis gigantea and Sarcocystis tenella and comparing them with gene sequences derived from other taxa of the phylum Apicomplexa. The results obtained from this study do not reject the hypothesis of monophyly of Sarcocystis species, although the bootstrap data were inconclusive for some species.
Histochemical mapping of NADPH diaphorase in the nervous system of the parasitic nematodeAscaris suum
Authors: Bascal Z. A. , Montgomery A. , Holden-Dye L. , Williams R. G. , Walker R. J.
Published: June 2009

NADPH diaphorase has recently been discovered to be responsible for neuronal nitric oxide (NO) synthase activity in mammals. It thus serves as a histochemical marker for the localization of NO synthase in the nervous system. The histochemical technique was used to map out potential NO-producing neurones in the nervous system of the parasitic nematode,Ascaris suum. Positive staining for NADPH diaphorase was present in various parts of the central nervous system, in particular within selective cell bodies and fibres in the ventral ganglion, the retrovesicular ganglion, ventral and dorsal cords and sublateral lines. Intense staining was also present in the motorneurone commissures, indicating a potential role for NO as a neurotransmitter at the neuromuscular junction. NADPH disphorase-positive neurones were not confined to the central nervous system. Selective staining was also present in the enteric nervous system, in particular the pharynx and in the peripheral nervous system innervating the sensory organs.
The human anion transport protein, band 3, contains a CD36-like binding domain forPlasmodium falciparum-infected erythrocytes
Authors: Crandall I. , Sherman I. W.
Published: June 2009

Epitope mapping of a murine monoclonal antibody (mAb), 5H12, prepared against livePlasmodium falciparum-intected red blood cells indicated that the epitope consisted of amino acid residues 474–487 of the human anion transport protein, band 3. mAb 5H12 enhanced cytoadherence, but inhibited the CD36-like mediated resetting. A synthetic peptide based on the sequence of the epitope (FSFCETNGLE) blocked both resetting and cytoadherence, suggesting that this amino acid sequence may form the CD36-like receptor. The CD36-like region of band 3 was antigenically distinct from platelet or endothelial CD36.
Dissociation of early and late protective immunity to the nematodeNippostrongylus brasiliensisin Brown Norway and Fischer-344 rats
Authors: Uchikawa R. , Yamada M. , Matsuda S. , Tegoshi T. , Nishida M. , Kamata I. , Kuroda A. , Arizono N.
Published: June 2009

Worm expulsion of, and IgE and interferon (IFN)-γ responses to,Nippostrongylus brasiliensiswere studied in 2 rat strains, Brown Norway (BN) and Fischer (F)-344. BN rats expelled the majority of worms by day 14 post-infection (p.i.) with approximately 6% of worms surviving for at least 3 weeks. In F-344 rats, worm expulsion was delayed by 2 days relative to that in BN, while the numbers of residual worms were significantly fewer than in BN, suggesting that different immune mechanisms are involved in early and late phases of immunity. Total serum IgE, as well asin vitroIgE production by mesenteric lymph node (MLN) cells, was increased 2 weeks p.i., the levels being markedly higher in BN than in F-344 rats. Serum rat mast cell protease II was also increased more significantly in BN than in F-344 rats. In contrast, production of IgG2a and IFN-γ by MLN and spleen cells was found to be higher in F-344 than in BN rats. These results indicate that the early worm expulsion is correlated with the host IgE and mast cell responsiveness, whereas the persistence of infection in the late period may be controlled by different immune mechanisms.