bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction: Ecological impact of parasitism on wildlife host populations
Authors: Grenfell B. T. , Gulland F. M. D.
Published: June 2009

The study of parasite population dynamics has been one of the major developments in ecology over the last 15 years (Kennedy, 1975). The seminal articles of Crofton (1971) and Anderson & May (1978, 1979; May & Anderson, 1978, 1979) began this process by illustrating the potential role of parasites in regulating or destabilizing the dynamics of wildlife host populations. Since then, a variety of empirical and theoretical studies (reviewed by Grenfell & Dobson, 1995) have explored the role of parasites in natural populations. In parallel with these population dynamical developments, a growing interest in the evolutionary ecology of parasites has also led to a large literature, examining the evolutionary impact of parasites and the importance of host-parasite coevolution (Hamilton, 1982; May & Anderson, 1990; Lively & Apanius, 1995; Readet al.1995; Herre, this volume).
Factors affecting the evolution of virulence: nematode parasites of fig wasps as a case study
Authors: Herre E. A.
Published: June 2009

The natural history of fig-pollinating wasps and their associated species-specific nematodes allows the measurement of many parameters which are relevant to testing hypotheses concerning host-parasite ecology and evolution. Within fig wasps species, it is possible to estimate lifetime reproductive success of foundress wasps as a function of presence or absence of nematode parasitism (virulence). Across species, there is a wide range of host population structures which, in turn, results in a range of opportunities for either horizontal or vertical nematode transmission. Therefore, estimates of virulence can be related to opportunities for transmission across a group of closely related hosts and their parasites. Further, the dynamics of the nematode infections over ecological and short-term evolutionary timescales can be monitored, giving added insight into the interpretation of the virulence estimates. Moreover, several scales of longer term evolutionary relationships are either known directly from fossil evidence or can be inferred from molecular data, providing deeper temporal context for the observed patterns. Thiscombination of attributespermits detailed testing of hypotheses concerning the factors that potentially influence the evolution of virulence in host-parasite systems, and further, population and simulation models of the system that incorporate the parameter estimates can clarify the interpretation of how those factors act. There is little evidence suggesting that intermediate and long-term evolutionary relationships explain current levels of virulence. That is, it appears that virulence can change rapidly relative to speciation events, and that the nematodes do not tend to become ‘benign over time’. Instead, it appears that host population structure can influence the evolution of parasite virulence by affecting the relative opportunities for horizontal to vertical transmission, which, in turn, influences the relative costs and benefits of virulence to the nematodes. At one level, increased opportunities for horizontal transmission decouple the reproductive interests of the individual nematodes from those of the individual hosts that they are directly parasitizing, thereby reducing the cost of virulence to individual nematodes. At another level, increased opportunities of horizontal transmission also increases the relative frequency of hosts infected by multiple strains of nematodes. This promotes the evolution of more virulent forms by increasing the relative importance of within-host competition among nematode strains, thereby favouring strains that ‘eat more host sooner’. An interesting property of the fig-nematode systems is that the proportion of infected hosts does not change dramatically through time. This finding implies that there can be considerable negative effects on survival of infected hosts in addition to the previously documented reductions in fecundity of infected foundresses, because the latter are insufficient to account for the observed stability of wasp infection rates.
Inhibitory action of the anti-malarial compound atovaquone (566C80) against Plasmodium berghei ANKA in the mosquito, Anopheles stephensi
Authors: Fowler R. E. , Billingsley P. F. , Pudney M. , Sinden R. E.
Published: June 2009

The activity of atovaquone against Plasmodium berghei ANKA during sporogonic development has been examined. Anopheles stephensi mosquitoes were fed on gametocyte infected mice which had been treated 8 h previously with atovaquone or diluent alone. Mosquito midguts were examined for oocysts, and salivary gland infections were estimated using an ELISA for the circumsporozoite protein (CSP). The number of oocysts per midgut fell by at least 97% when mosquitoes were fed on mice dosed with 0·1–10 mg atovaquone/kg body weight. This was paralleled by a decrease in the prevalence of oocyst-infected mosquitoes from 70–90% in controls to 40% or 10% respectively. No oocysts were observed at a dose of 100 mg/kg. CSP ELISA results indicated that mosquitoes fed on atovaquone failed to produce sporozoites. Mosquitoes which fed on gametocytaemic, atovaquone-treated mice (0·1–100 mg/kg) did not transmit malaria to naive mice. These results demonstrate that atovaquone has a highly potent inhibitory activity against the mosquito stages of P. berghei.
Schistosoma mansoni: immunolocalization of two different fucose-containing carbohydrate epitopes
Authors: Köster B. , Strand M.
Published: June 2009

We have used two monoclonal antibodies, 128C3/3 and 504B1, to immunolocalize their carbohydrate epitopes in different developmental stages ofSchistosoma mansoni. Both epitopes contain fucose: mAb 128C3/3, as we have shown previously, recognizes fucose in a novel, possibly internal linkage (Leveryet al.1992) while mAb 504B1, as we show here, bound to the Lexepitope, which contains fucose α1 → 3 linked toN-acetyl-glucosamine. The tissue expression of these epitopes was strikingly different and both elicit an immune response in infected hosts. The mAb 128C3/3-defined epitope was exposed on the surface of all larval stages but not on adult worms; however, it was found in the excretory system of adult worms of both sexes. In contrast, surface expression of the Lexepitope was initiated after the transformation of cercariae to schistosomula and was maintained throughout the adult life in both sexes.
Immunological relationships during primary infection withHeligmosomoides polygyrus: Th2 cytokines and primary response phenotype
Authors: Wahid F. N. , Behnke J. M. , Grencis R. K. , Else K. J. , Ben-Smith A. W.
Published: June 2009

The primary immune response to infection withHeligmosomoides polygyruswas studied in mice differing in response phenotype (fast-SWR, intermediate-NIH, slow-CBA). Marked IgGl and IgE but not IgG2a antibody responses were detected in infected mice and the former were more intense in fast compared with slow responder strains. Mastocytosis, MMCP-1, and the secretion of cytokines by mesenteric lymph node cells, following stimulationin vitroby Con A, were also more intense initially in SWR mice. Secretion of IL-4 declined in all strains by the 4th week of infection, irrespective of response phenotype. IL-10 was only produced briefly by SWR mice. However, the temporal patterns of secretion of IL-3 and IL-9 clearly distinguished fast from slow responder phenotypes. Following initial intense secretion of IL-3, production declined in all strains but in the 5–6th weeks enhanced secretion was evident in SWR and NIH mice and was sustained until week 10 p.i. In contrast, CBA mice never recovered from the initial down-regulation in weeks 3–4 and secretion declined to background levels by week 6 p.i. despite the continued presence of adult worms. Temporal changes in the secretion of IL-9 were very similar: secretion declined in CBA mice by week 6 p.i., whilst SWR and NIH mice continued to secrete high amounts. We suggest that fast and slow responder mice differ not only in their initial responsiveness to parasite antigens but also in their ability to sustain a Th2 response to the parasite and we propose that the latter is in part determined by their different susceptibilities to parasite-mediated immunomodulation. Only the fast responder strains can sustain a Th2 response of sufficient intensity to facilitate expulsion of adult worms.
The detection of AKH/HrTH-like peptides inAscaridia galliandAscaris suumusing an insect hyperglycaemic bioassay
Authors: Davenport T. R. B. , Eaves L. A. , Hayes T. K. , Lee D. L. , Isaac R. E.
Published: June 2009

Evidence for the presence of adipokinetic hormone/hypertrehalosaemic hormone (AKH/HrTH)-like peptides in the parasitic nematodesAscaridia galliandAscaris suumhas been obtained using insect bioassays which measure hyperglycaemic responses to peptides belonging to the AKH/HrTH family of insect hormones. A peptide fraction extracted from heads and tails ofAscaridia gallievoked a dose-dependent hyperglycaemic response when injected into the cockroach,Periplaneta americana. Maximal bioactivity was obtained with material that was equivalent to 38 mg (wet weight) of nematode. Bioactivity appeared to be highest in extracts from heads and tails of both male and female worms and could be fractionated into at least three peaks of hyperglycaemic activity by reversed-phase high-performance liquid chromatography. An extract from heads and tails ofA. suumalso evoked a hyperglycaemic response when injected into the cockroach,Blaberus discoidalis. The bioactivity was inactivated on incubation with pure endopeptidase 24.11, confirming the peptidic nature of the bioactive material. These results provide evidence for the existence of peptides related to the insect AKH/HrTH family of peptides in parasitic nematodes.
Cytoadherence-related neoantigens onPlasmodium falciparum(human malaria)-infected human erythrocytes result from the exposure of normally cryptic regions of the band 3 protein
Authors: Crandall I. , Sherman I. W.
Published: June 2009

Murine monoclonal antibodies (Mabs) were produced by vaccination of Balb/c mice with livePlasmodium falciparuminfected red cells (iRBC). The iRBC Mabs recognized altered forms of the human erythrocyte membrane protein band 3; however, these Mabs did not recognize the band 3 molecule in uninfected or ring-infected red cells. The location of epitopes was determined by studying the binding of the iRBC Mabs after selective proteolysis of band 3 as well as by the reactivity of these Mabs to synthetic peptides that corresponded to putative exofacial regions of band 3. Treatment of uninfected red cell membranes with trypsin under low ionic strength conditions resulted in exposure of cryptic epitopes of band 3 which were recognized by the iRBC Mabs. Several of the anti-iRBC Mabs (two of which were described previously) inhibited thein vitroadherence of infected erythrocytes to C32 amelanotic melanoma cells. A mouse polyclonal serum against a synthetic peptide based on an amino acid sequence motif of band 3 reacted (by immunostaining) only with the surface of iRBC and blocked adhesion. Thus, it appears that cryptic residues of the band 3 protein become exposed upon parasitization, and their presence contributes to the increased adhesiveness of theP. falciparum-infected red cell.
Analysis of the high molecular weight rhoptry complex ofPlasmodium falciparumusing monoclonal antibodies
Authors: Doury J.-C. , Bonnefoy S. , Roger N. , Dubremetz J.-F. , Mercereau-Puijalon O.
Published: June 2009

Twenty-one monoclonal antibodies, obtained after immunization of mice with erythrocytic stages ofPlasmodium falciparum, produced a double dot image in IFA. Immunoelectronmicroscopy indicated that the mAbs reacted with the rhoptries. Rhoptries are pear-shaped apical organelles, believed to be involved in invasion of the host cell by the parasite. The mAbs all immunoprecipitated the high molecular weight antigen complex. Some mAbs recognized on immunoblots only 1 protein of this complex, whereas others reacted with RhopH1 and RhopH3, or RhopH2 and RhopH3 or with the 3 proteins. An additional antigen of 52 kDa was also recognized by some of the mAbs. The epitopes defined by the mAbs were present in most of the 40P. falciparumstrains or isolates studied by IFA. Interestingly, the mAbs also reacted with high titres onP. vivaxandP. ovale, but produced images that did not indicate an apical location. The mAbs failed to react on the non-human malaria parasites studied,P. cynomolgiandP. inui. OnP. bergheiorP. chabaudiparasites, only 5 mAbs gave a positive reaction, labelling a large network outside the parasite. Finally, the mAbs did not react withP. falciparumsporozoites, indicating that the rhoptries of merozoites and sporozoites, the two invasive stages of the malaria life-cycle are equipped with distinct sets of proteins.
Coproantigen detection in rats experimentally infected with Strongyloides ratti
Authors: Nageswaran C. , Craig P. S. , Devaney E.
Published: June 2009

The possibility of coproantigen detection in the diagnosis of strongyloidiasis was investigated in rats experimentally infected with Strongyloides ratti. A capture ELISA was developed using affinity-purified polyclonal antibodies raised in rabbits against adult and filariform larval somatic antigens. The first detection of coproantigen coincided with patency and the coproantigen level remained elevated even when the parasite count was low. Following challenge infection, when examination of stool for larvae or ova was negative, coproantigen was detected by anti-adult somatic capture ELISA. Despite the use of antisera raised against crude worm extracts, the test was specific showing only low cross-reactivity with Necator americanus and Syphacia muris.
Naturally acquired infections with Leishmania enriettii Muniz and Medina 1948 in guinea-pigs from São Paulo, Brazil
Authors: Machado M. I. , Milder R. V. , Pacheco R. S. , Silva M. , Braga R. R. , Lainson R.
Published: June 2009

Two domestic guinea-pigs (Cavia porcellus), bought in Pinheiros, São Paulo State, Brazil, were taken by their owners a farm in the rural district of Capão Bonito, close to the Atlantic Forest, São Paulo, where they both developed tumour-like and ulcerating lesions on the ears. The causative agent was identified as Leishmania (L.) enriettii, based on biological characters and isoenzyme profiles. Sources of the parasite in wild mammals, and the possible sandfly vector species discussed.
Neoglycosylated liposomes as efficient ligands for the evaluation of specific sugar receptors on macrophages in health and in experimental leishmaniasis
Authors: Dutta M. , Bandyopadhyay R. , Basu M. K.
Published: June 2009

Receptors interacting with terminal sugars as ligands are involved in the binding ofLeishmania donovanipromastigotes to the macrophage surface and their subsequent internalization. Mannose and glucose are specifically involved in the binding process. Decreased binding occurs to macrophages already infected withL. donovanieitherin vivoorin vitro. When mannose- or glucose-bearing liposomes are used as ligands the binding shows similar trends and the percentage inhibition of binding with mannose-bearing liposomes increases when compared to that for the glucose-bearing ones. The decreased binding of the ligand seems to be due to a decrease in the number of receptors after infection. The affinity of the ligands for the binding sites either on the normal macrophages or on the infected macrophages apparently remains the same. The results based on the incorporation of [3H]phenyl alanine and supported by the binding of glycosylated liposomes to both infected and non-infected macrophages suggest that protein synthesis, in general, is suppressed inL. donovaniinfected macrophages thus affecting also mannose/glucose receptor protein synthesis, resulting in fewer receptors on the macrophage surface.
Maternal transfer of antibodies induced by infection withEimeria maximapartially protects chickens against challenge withEimeria tenella
Authors: Smith N. C. , Wallach M. , Petracca M. , Braun R. , Eckert J.
Published: June 2009

Infection of breeding hens withEimeria maximainduces production ofEimeria-specific IgG antibodies which are transferred to hatchlings via the egg yolk and confer a high degree of maternal immunity against homologous challenge and partial immunity to infection with another important species,Eimeria tenella. As an example, in an experiment using hatchlings from eggs collected between days 28 and 39 after infection of the hens with 20 000 sporulatedE. maximaoocysts, control chicks (challenged with 100 sporulated oocysts) excreted 6·8±1·2 million (mean±s.e., n = 10) or 5·8±1·2 million (n = 8) oocysts ofE. maximaorE. tenella, respectively, compared to 0·9±0·4 million (n = 5)E. maximaoocysts or 2·2±0·4 million (n = 9)E. tenellaoocysts excreted by hatchlings of infected hens. This represents an 87% reduction in oocyst excretion with regard toE. maximaand a 62% reduction in oocyst excretion with regard toE. tenellain the progeny of the infected hens. In another experiment, eggs were collected from days 28 to 37 and again from days 114 to 123 after infection of the hens withE. maximaand hatchling oocyst excretion rates were 82% and 62%, respectively, reduced forE. maximaand 43% and 41%, respectively, reduced forE. tenellain the progeny of hens infected withE. maximacompared to the progeny of uninfected hens. ELISA and Western blot analyses of maternally-derived IgG revealed a high degree of cross-reactivity to antigens ofE. maximaandE. tenella. Thus, maternally-derived, IgG-mediated cross- resistance to different species ofEimeriaoccurs in the chicken, most likely as a result of cross-recognition of conserved epitopes or proteins.
Attenuation ofSchistosoma mansonicercariae with a molluscicide derived fromMillettia thonningii
Authors: Perrett S. , Whitfield P. J. , Bartlett A. , Sanderson L.
Published: June 2009

A chloroform extract of molluscicidal plant secondary compounds from the seeds of a West African legumeMillettia thonningiiwas used to attenuate cercariae ofSchistosoma mansoniprior to infection of NMRI female mice. Exposure of cercariae to 0·3, 0·6, 1·3, 2·5, 10 or 20 mg/l concentrations of extract for 30 mm, immediately before standardized infection, was associated with a concentration-dependent decline in worm establishment at 55 days post-infection. The mean numbers of adult worms established declined from about 17 worms/mouse with control cercariae and those exposed to 0·3 mg/lMillettiato 0·1 worms/mouse after 10 mg/l pre-treatment. Mice exposed to cercariae after 20 mg/l pre-treatment had no adult worms at 55 days post-infection. The activities of cercariae 30 mm after exposure toMillettiaextract at concentrations up to 2·5 mg/l were similar to those of control larvae: none was immobile. Exposure to higher concentrations ofMillettiaprogressively reduced swimming activity and increased the proportion of immobile cercariae. After pretreatment with 20 mg/lMillettiathe majority of larvae were immobile. Levels of anti-parasite antibodies (estimated by ELISA assay using an adult worm-based antigen preparation) rose between 21 and 55 days p.i. with control cercariae and those pre-treated with 2·5 mg/lMillettia. After 5 mg/l pre-treatment, cercariae induced a reduced antibody rise, while mice exposed to cercariae after 10 mg/l pre-treatment showed no rise in anti-parasite antibody levels. These results are discussed in the context of protocols which could possibly useMillettia-attenuated cercariae to induce useful levels of protection in mice towards further cercarial challenge.
The effect of Toxoplasma gondii and other parasites on activity levels in wild and hybrid Rattus norvegicus
Authors: Webster J. P.
Published: June 2009

Using both correlational and experimental evidence, the relationship between parasite load and host activity was assessed in brown rats, Rattus norvegicus. Two hypotheses were tested – (1) that parasites with indirect life-cycles, involving transmission between a prey and its predator, will alter the activity of the intermediate host so as to increase its susceptibility to predation by the definitive host and (2) that activity levels in parasitized rats would be increased rather than decreased. Four groups of rats (n = 140) were examined. One group (n = 50) were wild brown rats trapped from 3 UK farmsteads, with naturally occurring parasites. The others were purpose-bred wild/laboratory hybrid rats with experimentally induced parasitic infections of either (n = 15) adult-acquired or (n = 15) congenitally-acquired Toxoplasma gondii (an indirect life-cycle parasite), or (n = 15) Syphacia muris (a direct life-cycle parasite). Uninfected hybrid rats (n = 45), matched for sex, age and weight, served as controls. Rats were housed individually in outdoor cages, and their activities were recorded on video-tapes for 6 non-consecutive 10 h nights. Exercise wheels were also available for the hybrid rats. Out of 6 parasite species detected in the wild rats, T. gondii was the only one which required predation by a definitive host to complete its life-cycle, and was also the only parasite to be associated with higher activity levels in infected than uninfected rats. Hybrid rats infected with T. gondii were also more active than those uninfected, whereas there were no differences in activity levels between S. muris infected and uninfected rats. This study shows that the indirect life-cycle parasite T. gondii can influence the activity of its intermediate host the rat. I suggest that this may facilitate its transmission to the cat definitive host.
The potential of vervet monkeys (Cercopithecus aethiops) and baboons (Papio anubis) as models for the study of the immunology of Echinococcus granulosus infections
Authors: Rogan M. T. , Marshall I. , Reid G. D. F. , Macpherson C. N. L. , Craig P. S.
Published: June 2009

Nine vervet monkeys and nine baboons were infected with eggs of Echinococcus granulosus per as. Six of the vervets and one of the baboons possessed hydatid cysts at autopsy, 15–28 months post-infection. The sequential IgG response to hydatid fluid and protoscolex antigens showed considerable inter-animal variation. Infected vervets and baboons became seropositive after an average of 8 months post-infection. Considerable fluctuation in the IgG response was observed, particularly to the hydatid fluid antigen which, in humans, may contribute to the existence of a significant proportion of seronegative individuals. Vervets, in particular, may be useful to study immunological events associated with exposure, development and resolution of hydatid disease in outbred human populations.
Analysis of lectin- and snail plasma-binding glycopeptides associated with the tegumental surface of the primary sporocysts ofSchistosoma mansoni
Authors: Johnston L. A. , Yoshino T. P.
Published: June 2009

Carbohydrates associated with the tegumental surface ofSchistosoma mansoniprimary sporocyst may serve as potential receptors for mediating recognition by the internal defence system of the molluscan host,Biomphalaria glabrata. Therefore, a combination of SDS-PAGE and lectin probe analyses were carried out on biotin-labelled tegumental glycopeptides as a first step to defining the carbohydrates expressed at the sporocyst surface. The majority of surface polypeptides, ranging in relative molecular masses from 27 to 113 kDa, reacted with horseradish peroxidase-labelledCanavalia ensiformis(Con A),Erythrina corallodendron(ECA),Glycine max(SBA) andTriticum vulgaris(WGA) lectins indicating that most, if not all, tegumental proteins are glycosylated. However, differences in the binding of some lectins to individual glycopeptides suggest a degree of heterogeneity in the structure/composition of sugar moieties comprising these surface glycoconjugates. This notion is supported by the finding that the fucose-specificTetragonolobus purpureas(TPA) lectin only reacted with approximately 50% of glycopeptides identified at the tegumental surface. Experiments employing biotin-labelled plasma (cell-free haemolymph) fromS. mansoni-susceptible and -resistantB. glabratasnails as probes, further demonstrated that many of the identified surface glycoproteins also serve as plasma-binding sites for both snail strains. Binding interactions between plasma and sporocyst surface glycoproteins appeared to be, at least in part, mediated by carbohydrates since periodate treatment of sporocyst proteins or pre-incubation of plasma with the glycoproteins, fetuin or mucin, resulted in a decrease in plasma reactivity to blotted larval proteins.
The impact of variations in temperature on early Plasmodium falciparum development in Anopheles stephensi
Authors: Noden B. H. , Kent M. D. , Beier J. C.
Published: June 2009

The effect of temperature on early Plasmodium falciparum development was examined in Anopheles stephensi. The rates of both ookinete development and bloodmeal digestion were lengthened as temperatures decreased from 27 to 21 °. However, low temperatures (21–27 °) did not significantly influence infection rates or densities of either ookinetes or oocysts. In contrast, high temperatures (30 and 32 °) significantly impacted parasite densities and infection rates by interfering with developmental processes occurring between parasite fertilization and ookinete formation, especially during zygote and early ookinete maturation. This study demonstrates clearly that temperature affects the sporogonic development of P. falciparum in anophelines by altering the kinetics of ookinete maturation. These studies not only confirm the ookinete as the key development stage affecting the probability of vector infectivity, they provide new insights into the epidemiology of P. falciparum infections.
The blood-stages of Plasmodium georgesi, P. gonderi and P. petersi: course of untreated infection in their natural hosts and additional morphological distinctive features
Authors: Poirriez J. , Dei-Cas E. , Dujardin L. , Landau I.
Published: June 2009

In the blood of a Cercocebus albigena and of a C. galeritus agilis monkey, the infection with Plasmodium gonderi was found to follow its well-known chronic course; P. georgesi seemed to occur as a relapsing type of malaria parasite; P. petersi was found for only a few days and at a low level in C. albigena (end of an attack?). As shown by using polarized light, the pigment granules appeared mostly as fine dots in P. georgesi, short rods in P. gonderi and long needles in P. petersi. The three species can be distinguished by the morphological appearance of the nucleus of the young trophozoites, and also by the measurement of its surface area (Sa): small round nucleus (Sa= 0·81 ± 0·06 μm2) in P. gonderi, large 2-coloured nucleus (Sa= 1·43 ± 0·21 μm2) in P. petersi, and long crescent-shaped nucleus (Sa= 2·18±0·25 μm2) in P. georgesi. The first colour illustrations of the blood-stages of P. georgesi are presented. The dynamics of single and mixed blood infections in primate malaria parasites are discussed, with a proposal to classify them into 3 types.
Plasmodium yoelii nigeriensis: the effect of high and low intensity of infection upon the egg production and bloodmeal size of Anopheles stephensi during three gonotrophic cycles
Authors: Hogg J. C. , Hurd H.
Published: June 2009

Anopheles stephensi mosquitoes showed a reduction in fecundity over 3 successive gonotrophic cycles, after becoming infected with Plasmodium yoelii nigeriensis. This effect could be observed at high oocyst burdens (> 75) or at low oocyst burdens (mean of 4·36). Mean bloodmeal size of the infected mosquitoes was significantly reduced only when feeding upon a mouse with a high gametocytaemia and the conversion of the bloodmeal into eggs by the infected mosquitoes was disrupted. Patterns of infected mosquito mortality, over the 3 gonotrophic cycles, varied with severity of infection. Although in 1 case increased mortality and decreased bloodmeal size may have affected fecundity, this could not have accounted for all of the observed fecundity reduction. We propose that other, unknown parasite related factors, are involved.
Identification and properties of a neuropeptide-degrading endopeptidase (neprilysin) ofAscaris suummuscle
Authors: Sajid M. , Isaac R. E.
Published: June 2009

We have previously identified in membranes of the locomotory muscle ofAscaris suuma phosphoramidon-sensitive endopeptidase which hydrolyses the neuropeptide AF1 (Lys-Asn-Glu-Phe-Ile-Arg-Phe-NH2) by cleavage of the Glu3-Phe4bond (Sajid & Isaac, 1994). We have determined the properties of this neuropeptide-degrading enzyme ofA. suummuscle using AKH-I (ρGlu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2) and [D-Ala2, Leu5]enkephalin as convenient endopeptidase substrates. Phosphoramidon, thiorphan and SQ 28603, potent inhibitors of mammalian neprilysin (neutral endopeptidase, endopeptidase 24.11), inhibited the endopeptidase activity towards AKH-I with IC50values of 0·13 μM, 22 μM and 6·3 μM, respectively. Two other neprilysin inhibitors (SCH 32615 and SCH 39370) and the bivalent metal ion chelators, EDTA (1 mM) and 1, 10bis-phenanthroline (1 mM) failed to inhibit the nematode enzyme. The endopeptidase had a neutral pH optimum and a significant proportion (45%)of the enzyme activity partitioned into the detergent-rich phase of Triton X-114, indicating that the enzyme is an integral membrane protein. The muscle enzyme also attacked [D-Ala2, Leu5]enkephalin cleaving the Gly3-Phe4bond and this hydrolytic activity was inhibited by phosphoramidon and thiorphan (IC50, 0·28 ρM and 15·8 ρM, respectively) but not by EDTA and 1,10bis-phenanthroline. The phosphoramidon-sensitive endopeptidase activity was detected on intact muscle cells prepared by collagenase treatment of the body wall musculature, indicating that endopeptidase is accessible to peptide molecules that interact with the cell surface.
A modified binomial model that describes the infection dynamics of the entomopathogenic nematode Steinernema feltiae (Steinernematidae; Nematoda)
Authors: Hay D. B. , Fenlon J. S.
Published: June 2009

Third-stage (dauer) juveniles of the entomopathogenic nematode Steinernema feltiae from 3 laboratory populations were tested for infectivity to larvae of the sciarid fly Lycoriellia solani. Bioassay experiments were done to assess the effects of nematode application density, exposure time and host density on the proportion of individuals that established infection. When dauer stages were presented to a host singly, establishment rates of 28, 26 and 18% were obtained for the 3 populations, but the presence of conspecifics consistently increased the rate of establishment to 42, 33 and 21% respectively, at 20 nematodes per host. A modified binomial model was developed to show that nematode establishment was not related to application density in a linear fashion, as initial infection facilitated secondary colonization. The data suggest that 3 subpopulations of nematodes may be distinguished by their infection behaviour: a first group of individuals with the behavioural propensity to initiate infection in unparasitized insects, a second that only invaded infected hosts, and a third group of non-invaders that failed to establish in L. solani.
Mode of nutrition of the larvae of the filarial nematode Brugia pahangi
Authors: Beckett Evelyn B. , Boothroyd B.
Published: June 2009

(1) Light-microscopic observations were made on B. pahangi larvae at various stages of development in stained serial sections of A. aegypti thoraces, and on 8-to 9-day 2nd-stage live, unstained larvae.

(2) Six-day larvae situated in A. aegypti flight muscle, and isolated 8- to 9-day 2nd-stage larvae, were examined with the electron microscope.

(3) Results showed that host-muscle mitochondria which appeared to be morphologically intact aggregated outside the larvae at the head and tail ends and were present from 6 days onwards in the oesophagus and in the midgut. Those in the oesophagus were unchanged; some of those in the midgut were intact, others showed varying degrees of disintegration suggestive of digestion. Host-muscle mitochondria are therefore likely to be a source of nutrients for B. pahangi larvae during the last third of their intramuscular developmental phase.

Dr W. W. Macdonald, of the Liverpool School of Tropical Medicine, kindly supplied the infected mosquitoes, and offered valuable advice in the course of this work. Miss M. A. Johnson assisted with the care of the mosquitoes.

We are particularly indebted to Mr David John for his patient work in preparing the filariae for electron-microscopic observation. Mrs J. Oliver assisted with some of the histological preparations.

We are pleased to acknowledge the financial assistance of the Royal Society towards the purchase of the ultramicrotomes used in the course of this work.
Larvae of the Ixodes ricinus complex of species
Authors: Snow Keith R. , Arthur Don. R.
Published: June 2009

An account is given of the morphological characteristics of larvae of four species of the Ixodes ricinus complex, namely I. ricinus, I. persulcatus, I. pacificus and I. nipponensis. Particular reference is made to chaetotaxy and its importance in differentiating larvae of closely related species is emphasized.

We are grateful to Dr G. Owen Evans for discussion on matters on chaetotaxy.
The quantity of blood imbibed by Hyalomma anatolicum anatolicum Koch, 1844 (Ixodoidea, Ixodidae)
Authors: Snow Keith R.
Published: June 2009

1. The weight of blood ingested by all stages of H. anatolicum anatolicum has been determined and from the results a direct relationship appears to exist between the weights of replete adults and their blood content. In engorged nymphs the relationship was subject to some variations, while in fully fed larvae no such correlation was apparent, indicating the ingestion of a large proportion of extravascular fluids.

2. It was found that all instars concentrate the imbibed blood by the elimination of water. In larvae the concentration is by a factor of at least 5·25, in nymphs 3·4, in females 2·1 and in males 1·4.

3. A correlation was found between the external colour of fully engorged larvae and the quantity of blood imbibed.

I wish to thank Dr R. P. Chaudhuri for providing the original specimens of H. anatolicum anatolicum from which the culture was started, and Professor Don. R. Arthur for reading the manuscript and for his advice and assistance.
Extended schizogony of Eimeria mivati in betamethasone-treated chickens
Authors: Long P. L. , Rose M. Elaine
Published: June 2009

Cortisone treatment of BL chickens given oocysts of Eimeria mivati resulted in the production of greater numbers of oocysts in the faeces and a prolonged patent period.

Schizonts were seen in sections of the intestines of treated birds up to the 24th day after oocyst inoculation although none was seen in control chickens after the 8th day. These late schizonts resembled those of the 3rd and 4th generations recorded for this species but may be those of a generation not yet described.

The depletion of intestinal lymphoid tissue in cortisone-treated birds is noted. The findings are discussed with reference to host-parasite relationships.

We wish to thank the scientific assistants and senior poultry attendant of the department for their help throughout the work.
Description of a model to simulate effects of Eimeria acervulina infection on broiler production
Authors: Henken A. M. , Graat E. A. M. , Ploeger H. W. , Carpenter T. E.
Published: June 2009

A simulation model for effects of Eimeria acervulina infection on technical and economic characteristics in broiler production is presented. The model describes development over time of the growth depression, feed intake reduction, and decrease in feed efficiency associated with infection. The model also shows a phase of compensatory growth during which earlier negative effects are counterbalanced, at least partly. Major assumptions made were: infection with E. acervulina occurs in each flock; production is affected in each flock; compensatory growth takes place because immunity develops and cell regeneration occurs. The results show that the pattern of development of the production characteristics during a flock cycle depends on the initial contamination level. Both a high and low initial contamination level results in a lower average daily gain, a worse feed to gain ratio, and a reduced net revenue compared to an intermediate contamination level.
Purification and biochemical characterization of acetylcholinesterase (AChE) from the excretory/secretory products ofTrichostrongylus colubriformis
Authors: Griffiths G. , Pritchard D. I.
Published: June 2009

Acetylcholinesterase (AChE) has been purified from the excretory/secretory (ES) products ofTrichostrongylus colubriformis(using edrophonium chloride linked to epoxy-activated Sepharose) with yields of 40–50%. Purity was confirmed by polyacrylamide gel electrophoresis (using silver [protein] and Karnovsky [activity] stains) and measurement of specific AChE activity. Further analysis of the purified fractions by gel filtration and sucrose density gradient techniques revealed the existence of 2 forms of hydrophilic AChE (Mr189 and 80 kDa). From the data we deduce these to be the globular monomer and dimer, G1 and G2 forms of AChE. Inhibition studies using BW284C51, iso-OMPA and excess substrate, along with substrate specificity studies, show both forms to be true acetylcholinesterases. We are currently assessing the protective immunogenicity of purified AChE in sheep.
Spermiogenesis and spermatozoan ultrastructure inPolymorphus minutus(Acanthocephala)
Authors: Whitfield P. J.
Published: June 2009

The spermiogenesis and spermatozoan morphology of the palaeacanthocephalan,P. minutuswere studied by a variety of electron microscopical methods.

Spermiogenesis occurs in syncytial clusters of spermatids exhibiting synchronous development. The outstanding events of the spermiogenic process are an enormous elongation of the spermatid nucleus and the eventual breakdown of the spermatid nuclear envelope.

The mature spermatozoon is a filiform cell about 60 μm long and motile by propagated undulations. It consists of two parallel elongate components, the single flagellum and the spermatozoan body. The former has a 9 + 2 tubule organization and the latter contains glycogen granules and membrane-bound dense inclusions as well as a region of condensed chromatin of nuclear origin. No mitochondria appear to be present.

In the University of Cambridge I should like to thank Professor H. Goodwin for the provision of electron microscope facilities and Mr B. Chapman for teaching me to use them. At King's College, London I am indebted to Professor D. R. Arthur and Professor F. R. Whatley for facilities and Mr H. Edge for excellent technical assistance. The work reported in this paper was initiated during the tenure of an S.R.C. Research Studentship and completed whilst in receipt of a Research Fellowship from the Nuffield Foundation.
Characterization of membrane proteins exported from Plasmodium falciparum into the host erythrocyte
Authors: Johnson D. , Günther K. , Ansorge I. , Benting J. , Kent A. , Bannister L. , Ridley R. , Lingelbach K.
Published: June 2009

Plasmodium falciparum is an intracellular parasite of the red blood cell. During development it exports proteins which are transported to specific locations within the host erythrocyte. We have begun to identify and characterize exported membrane proteins of P.falciparum in order to obtain specific marker molecules for the study of the mechanisms involved in the distribution of parasite-derived proteins within the host cell. In this report we describe the characterization of a 35 kDa protein which is recognized by a monoclonal antibody. The protein is tightly associated with membranes isolated from infected erythrocytes; it is resistant to extraction with alkali and soluble after treatment with detergents. It is located at the membrane of the parasitophorous vacuole and in membrane-bound compartments which appear in the cytoplasm of the infected erythrocyte. The protein co-localizes with the previously described exported protein-1 (exp-1). Considering its localization and physical similarities to exp-1, we name the 35 kDa protein the exported protein-2 (exp-2).
Haemoglobin inhibits the development of infective promastigotes and chitinase secretion inLeishmania majorcultures
Authors: Schlein Y. , Jacobson R. L.
Published: June 2009

Haemoglobin or blood in the growth medium ofLeishmania majorinhibited the formation of infective promastigotes and the secretion of chitinases. Inoculation of mice with stationary-phase parasites from control medium caused infections in 20/29 mice, compared to 3/20 mice injected with parasites grown with 10% rabbit blood, or 1/30 mice that received parasites grown with rabbit haemoglobin. The concentration of peanut lectin (PNA) required to agglutinate promastigotes was used as an index of their infectivity, ranging from a high concentration for infective populations to a low concentration for relatively non-infective populations. Agglutination of 50% of the parasites from control medium or from medium containing rabbit haemoglobin required 4·1 μg PNA/ml and 0·1 μg PNA/ml, respectively. Chitinase activities/107parasites decreased from 4·8 units chitinase and 12·5 unitsN-acetylglucosaminidase (NAGase) in the control to 2·0 units chitinase and 8·5 units NAGase in cultures containing rabbit haemoglobin. Rabbit, human, bovine and pigeon haemoglobins had various inhibitory effects on the activity of chitinases and not on the virulence, as expressed by PNA agglutination. The relevance of the results to the cycle ofLeishmaniais discussed.
FMRFamide-related peptides (FaRPs) in nematodes: occurrence and neuromuscular physiology
Authors: Maule A. G. , Bowman J. W. , Thompson D. P. , Marks N. J. , Friedman A. R. , Geary T. G.
Published: June 2009

The occurrence of classical neurotransmitter molecules and numerous peptidic messenger molecules in nematode nervous systems indicate that although structurally simple, nematode nervous systems are chemically complex. Thus far, studies on one nematode neuropeptide family, namely the FMRFamide-related peptides (FaRPs), have revealed an unexpected variety of neuropeptide structures in both free-living and parasitic species. To date 23 nematode FaRPs have been structurally characterized including 12 from Ascaris suum, 8 from Caenorhabditis elegans, 5 from Panagrellus redivivus and 1 from Haemonchus contortus. Ten FaRP-encoding genes have been identified in Caenorhabditis elegans. However, the full complement of nematode neuronal messengers has yet to be described and unidentified nematode FaRPs await detection. Preliminary characterization of the actions of nematode neuropeptides on the somatic musculature and neurones of A. suum has revealed that these peptidic messengers have potent and complex effects. Identified complexities include the biphasic effects of KNEFIRFamide/KHEYLRFamide (AF1/2; relaxation of tone followed by oscillatory contractile activity) and KPNFIRFamide (PF4; rapid relaxation of tone followed by an increase in tone), the diverse actions of KSAYMRFamide (AF8 or PF3; relaxes dorsal muscles and contracts ventral muscles) and the apparent coupling of the relaxatory effects of SDPNFLRFamide/SADPNFLRFamide (PF1/PF2) to nitric oxide release. Indeed, all of the nematode FaRPs which have been tested on somatic muscle strips of A. suum have actions which are clearly physiologically distinguishable. Although we are a very long way from understanding how the actions of these peptides are co-ordinated, not only with those of each other but also with those of the classical transmitter molecules, to control nematode behaviour, their abundance coupled with their diversity of structure and function indicates a hitherto unidentified sophistication to nematode neuromuscular intergration.
Molecular cloning andin vitroexpression ofC. elegansand parasitic nematode ionotropic receptors
Authors: Fleming J. T. , Baylis H. A. , Sattelle D. B. , Lewis J. A.
Published: June 2009

The free living nematode,C. elegansis understood at a level of detail equalled by few other organisms, and much of the cell biology and sequence information is proving of considerable utility in the study of parasitic nematodes. Already,C. elegansprovides a convenient vehicle for investigating anthelmintic drug action and resistance mechanisms. Among the ionotropic receptors, with their important roles in the behaviour and development of the organism, are targets for anthelmintics. The subunits of nicotinic acetylcholine receptors ofC. elegansform a large and diverse multigene family. Members of this family are among the 11 genes associated with resistance to the anthelmintic drug levamisole.
Resistance toEimeriainfections in the chicken: the effects of thymectomy, bursectomy, whole body irradiation and cortisone treatment
Authors: Rose M. Elaine , Long P. L.
Published: June 2009

Surgical bursectomy or thymectomy at day old had little effect on primary or subsequent infections withE. brunetti or E. maxima.

Whole body irradiation of day-old chickens with 700 or 750 R did not affect the development of immunity to theseEimeriaspp., but in some experiments it affected oocyst production during initial infections.

In one of four trials, birds surgically bursectomized and irradiated produced twice as manyE. brunettioocysts during an initial infection as the irradiated only controls; in the remaining three trials, oocyst production in the operated birds was either similar to or slightly greater than that in the controls. Combined bursectomy and irradiation did not affect immunity to re-infection.

Combined thymectomy and irradiation had little effect on primary infections (increased oocyst output was found in only one of six trials) and no effect on subsequent immunity; mean body weights and circulating lymphocyte numbers were decreased but tuberculin sensitivity was reduced in only a small proportion of the birds, indicating that the cell mediated immune responses of the majority were not affected.

Small (0.75 mg) daily doses of cortisone acetate given to irradiated birds or irradiated thymectomized birds, did not affect resistance to reinfection withE. brunetti.

We wish to thank Dr B. M. Freeman for surgical bursectomy; Mr E. A. King, Department of Radiotherapeutics, University of Cambridge, for irradiation and members of the technical staff of the Parasitology Department for their willing and skilled assistance.
The production, transfer and assimilation of spermatophores by Entobdella soleae, a monogenean skin parasite of the common sole
Authors: Kearn G. C.
Published: June 2009

It has been shown that mating involving mutual exchange of spermatophores takes place in the skin-parasitic monogenean Entobdella soleae from Solea solea. The spermatophores are attached to the ventral surface of the body in the region of the vaginal opening and they are sucked into the vagina after mating by muscular contractions of the vaginal region.

Mating takes place between young individuals with no vitellaria and between fully mature egg-laying adults but there is no evidence that self-fertilization takes place.

The apparatus which manufactures the spermatophores is described and the evidence indicates that spermatozoa are injected into the jelly-like matrix of the spermatophore as the matrix is being extruded into the surrounding sea-water.

I would like to thank the Director and Staff of the Laboratory of the Marine Biological Association at Plymouth for providing excellent facilities for this work and I am particularly grateful to Mr J. E. Green, who kindly fed and maintained infected soles at the Laboratory.