bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selection of specific genotypes ofgiardia intestinalisby growthin vitroandin vivo
Authors: Andrews R. H. , Chilton N. B. , Mayrhofer G. 
Published: June 2009

SUMMARYThis study examined whether allelic changes observed when clinical isolates ofGiardia intestinalismade in suckling mice were adapted toin vitrogrowth occurred as a result of gene switching (alternate isoenzymes) or through selection of organisms with different genotypes from mixed infections. Samples were compared electrophoretically at 20 enzyme loci. Marked allelic differences were detected between the uncloned clinical isolates grown in mice and the axenic cultures established from them. Furthermore, the allelic profiles of the uncloned isolates changed during the course ofin vivoorin vitrogrowth. In contrast, all clones produced from each isolate retained identical allelic profiles, regardless of whether they were grownin vivoorin vitro. These findings argue against gene switching as an explanation for the observed allozyme changes and support preferential selection of organisms with specific genotypes by growth conditions. The data indicate the presence of at least 2 and possibly up to 4 distinct genotypes within each clinical isolate. The genetic differences detected between clinical isolates in suckling mice were of similar magnitude to those that separate different axenic isolates ofG. intestinalisinto cryptic species. Conversely, the genetic differences between the isolates were limited when sampled after establishmentin vitro. These findings have significant implications for research onGiardiaand other medically important parasites and raise the possibility that culture may exert a similar selective bias on the genotypes isolated from infections with other parasitic protozoa.
Trichobilharzia ocellata infections in its snail host Lymnaea stagnalis: an in vitro study showing direct and indirect effects on the snail internal defence system, via the host central nervous system
Authors: Amen R. I. , De Jong-Brink M. 
Published: June 2009

SUMMARYIn this in vitro study we investigated whether previously described in vivo plasma-associated effects, that occurred in the period shortly after penetration of Trichobilharzia ocellata into the snail host Lymnaea stagnalis (1.5–72 h post-exposure; p.e.) were direct and/or indirect effects of parasite-derived factor(s). It was investigated whether the effect is mediated by the central nervous system (CNS) of the host. Phagocytic activity of the haemocytes was taken as a parameter for the activity of internal defence of the host. A number of preliminary experiments were performed. When the supernatant of in vitro cultured parasites (33 h; corresponding with their developmental stage in vivo when plasma-associated activation was found) was applied directly to monolayers of haemocytes, it appeared to enhance their phagocytic activity. No direct effect, however, was found with a supernatant of parasites cultured for a longer period of time (72 h; when, in vivo, a plasma-associated suppression was found). In this case, indirect suppression was detected: the parasites appeared to have released a factor that induced the CNS of the host to release material suppressing the activity of the internal defence system of the host. To date the nature of this factor is unknown.
Population dynamics of Sphaerospora dicentrarchi Sitja-Bobadilla et Alvarez-Pellitero, 1992 and S. testicularis Sitja-Bobadilla et Alvarez-Pellitero, 1990 (Myxosporea: Bivalvulida) infections in wild and cultured Mediterranean sea bass (Dicentrarchus labrax L.)
Authors: Sitja-Bobadilla A. , Alvarez-Pellitero P. 
Published: June 2009

SUMMARYThe population dynamics of Sphaerospora dicentrarchi and S. testicularis, myxosporean parasites of sea bass (Dicentrarchus labrax), was studied in different groups of cultured and wild fish. S. dicentrarchi prevalence was higher for wild fish (100%) than for cultured ones (70.5%). Infection levels increased with host age and there were no significant sex differences in cultured fish. Among parasitized organs, the gall bladder and intestine registered the highest infection levels in wild and cultured fish. A progressive increase in infection levels of S. testicularis was observed in cultured males during the spawning season in four consecutive periods. The evolution of the percentage of the different parasitic stages is pointed out. The infection seems to be related to water temperature and gonadal maturation.
Assessment of monoclonal antibodies toEchinococcus granulosusAntigen 5 and Antigen B for detection of human hydatid circulating antigens
Authors: Liu D. , Rickard M. D. , Lightowlers M. W. 
Published: June 2009

SUMMARYFour monoclonal antibodies (MAb) toEchinococcus granulosusAntigen 5 (Ag5) and Antigen B (AgB) were assessed in an enzyme-linked immunosorbent assay (ELISA) for detection of circulating antigens (CAg) in sera of human patients withE. granulosusinfection. Around 5·5–8% of 200 sera from 42 surgically proven hydatid patients contained detectable CAg by individual MAb. The combined detection rate for CAg, using four MAb, was 19% (38/200). Although hydatid CAg was detected by MAb in at least one serum sample from 21 of 42 patients, some patients remained negative in the assay regardless of the time when serum samples were taken (pre- or post-operatively), or of the continuing presence of hydatid cysts, their location or fertility. In addition, it was observed that the binding capacity of MAb for sheep hydatid cyst fluid antigen (SHCF) was somewhat reduced in the presence of normal human serum. The CAg detection assay would only be useful for assessment of hydatid infection status in patients with detectable CAg in serum samples.
A comparison of African Buffalo, N'Dama and Boran cattle as reservoirs of Trypanosoma vivax for different Glossina species
Authors: Moloo S. K. , Gettinby G. , Olubayo R. O. , Kabata J. M. , Okumu I. O. 
Published: June 2009

SUMMARYTeneral Glossina morsitans centralis were fed on the flanks of African buffalo, N'Dama or Boran cattle infected with Trypanosoma vivax IL 2337. The infected tsetse were maintained on goats and on day 25 after the infected feed, the surviving tsetse were dissected to determine the infection rates. The mean mature infection rates (% ± S.E.) in the tsetse fed on buffalo, N'Dama and Boran cattle were 34·3 ± 9·9, 33·7 ± 13·4 and 58·9 ± 7·1, respectively. Logistic regression analysis indicated that infection rates in the labrum and hypopharynx of the tsetse were significantly lower when fed on the infected buffalo or N'Dama than Boran cattle. Similarly, the risk of infection was significantly lower in male than female tsetse. When teneral G. m. centralis, G. pallidipes, G. p. gambiensis, G. brevipalpis and G. longipennis were fed simultaneously on either the buffalo cow, the N'Dama bull or the Boran steer infected with T. vivax IL 2337, the mature infection rates were higher in the two morsitans group than the two fusca group tsetse, whilst G. p. gambiensis was relatively refractory to the infection, irrespective of the host species on which they fed. Logistic regression analysis indicated that the infection rates in the labrum and hypopharynx were significantly different amongst the five tsetse species for each of the three infected host animals. Nevertheless, the trypanotolerant African buffalo and N'Dama cattle may serve as reservoirs of T. vivax infection as can trypanosusceptible Boran cattle.
Interactions between chemotherapy and immunity in bovine theileriosis
Authors: Cox F. E. G. 
Published: June 2009

SUMMARYIn bovine theileriosis the use of chemotherapy to control an infection sufficiently long to permit the establishment of a solid protective immune response has been developed as a routine vaccination procedure. Infections withTheileria parvaandT. annulatacan be prevented by the administration of carefully controlled numbers of sporozoites simultaneously with a long acting tetracycline and this form of immunization has been widely used for the control of East Coast fever in Africa with considerable success. In this review, the nature of the chemotherapy, the immune response and the interactions between chemotherapy and immunity in the development of infection-and-treatment immunization procedures are discussed.
Hypothesis: impaired immunity as a factor which contributes to the spread of drug-resistance
Authors: Doenhoff M. J. , Davies A. J. S. 
Published: June 2009

SUMMARYEvidence has accrued to indicate that host defence mechanisms enhance the efficacy of many of the drugs used to treat infectious diseases. Because of this, and also because of the likelihood of increased pathogen loads in immunoincompetent hosts, some infections are less likely to be completely cured by normal regimens of chemotherapy in individuals with drastically impaired immune responsiveness. In such circumstances natural selection could result in the accelerated emergence of drug-resistant pathogens.
Proteins on the surface of the malaria parasite and cell invasion
Authors: Holder A. A. 
Published: June 2009

SUMMARYThe malaria parasite exists in an extracellular form at several stages in its life cycle. Within the vertebrate host, sporozoites and merozoites have to invade specific cell types. Proteins on the surface of the parasite or externalized from specialized organelles have been implicated as ligands for receptors on the host cell surface. Direct binding studies have identified parasite proteins that interact with the target cell surface. Examination of the deduced amino acid sequences has allowed the identification of primary structural motifs which may have roles in this process. On the sporozoite, the circum-sporozoite protein and sporozoite surface protein-2, a protein initially located within micronemes, have been found to contain an amino acid sequence thought to be involved in mediating recognition of sulphated polysaccharides on the surface of a liver cell. On the merozoite, merozoite surface protein-1 may be involved in the initial recognition of red blood cells; this protein undergoes a complex series of modifications in the time between its synthesis as a precursor molecule and successful erythrocyte invasion. Other merozoite proteins located at the apical end of the parasite have been identified as erythrocyte or reticulocyte binding proteins.
Lung-worms (Nematoda: Pseudaliidae) of harbour porpoises (Phocoena phocoena) in Norwegian waters: patterns of colonization
Authors: Balbuena J. A. , Aspholm P. E. , Andersen K. I. , Bjørge A. 
Published: June 2009

SUMMARYWe studied the component community of lung-worms of the harbour porpoise, attempting to establish the relative importance of ecological and evolutionary factors on its development. The lungs of 64 porpoises by-caught in Norwegian waters were examined for helminths. Three pseudaliid species were detected. The porpoises appear to be readily colonized by lung-worms, the structure of the component community of calves being fairly similar to that of the remainder. Prenatal and/or transmammary infections might partly account for these early infections. However, host age was correlated with the number of lung-worm species, suggesting that the lung-worms may have heteroxenous cycles similar to other metastrongyloids. The lung-worm species tended to co-occur more often than expected by chance. This pattern is commonly observed in communities formed by phylogenetic relatives. Mean species richness of lung nematodes differed significantly among mammalian orders. However, species richness of marine species seemed very similar to those of most terrestrial species. This evidence suggests that phylogenetic factors seem more important than ecological ones in determining the number of lung-worm species in mammals.
The relationship between pattern and scale in parasite communities: a stranger in a strange land
Authors: Kennedy C. R. , Bush A. O. 
Published: June 2009

SUMMARYProblems of pattern and scale are considered in relation to helminth communities of freshwater fish by examining them at different hierarchical taxonomic and spatial scales, with a view to seeking generalizations of heuristic value, assessing the importance of phylogenetic and ecological determinants of community structure and improving understanding of unpredictable communities. Initially, communities were analysed at the level of salmonid genera, focusing onOncorhynchus, in its heartland in Canada: then inO. mykissthroughout its global range and finally in individual localities to which it has been introduced in Britain. In the heartland, communities are dominated by salmonid specialist helminths, forming a phylogenetic element: the minority ecological element comprises broad generalists and non-salmonid specialists. Most species except generic specialists are shared between host genera. As the distance to whichO. mykisswas translocated from its heartland increases, so generic specialists disappear first and then salmonid specialists decline. The community is thus increasingly composed of generalists and it also becomes increasingly poor. Helminths may be acquired from native salmonids and/or unrelated hosts, depending on availability. This same pattern is paralleled in individual localities in a restricted region: the phylogenetic element reflects the native salmonid species present and the ecological element the presence of other genera of fish, i.e. a supply-side situation. The change of scale in analysis has thus enabled the recognition of generalizations and patterns of heuristic value and improved the understanding of unpredictable communities by interpreting local variation as ecological ‘noise’ that often obscures fundamental patterns. In this and other taxa of fish, phylogenetic elements dominate helminth communities in the heartlands, but ecological elements dominate as the host increasingly becomes a stranger in a strange land.
Turnover of microfilariae in small mammals 2. Disintegration of microfilariae (Acanthocheilonema viteae) (Filarioidea: Nematoda) after intravenous injection into the jird,Meriones unguiculatus
Authors: Wenk P. , Kellermann E. , Hafner C. 
Published: June 2009

SUMMARYAfter i.v. injection of 305 × 103microfilariae (mf) per animal (50 g) into naive jirds, 50·8% of them could be recovered at autopsy 15 min later. Of these, 65·8% were calculated to be in the peripheral circulating blood (PCB) and were completely intact; 18·6% were recovered by perfusion of the lungs and 13·6% from the liver. In both organs about half the mf were associated with adherent lymphocytes and neutrophils but a few were partly disintegrated. Only 2·6% were recovered from the kidneys and the spleen. In long-term injection experiments using the same inoculum size the autopsy was done 15 min and 1, 3 and 6 weeks post-injection (p.i.) of mf into naive jirds. Throughout the experimental period the density of mf remained more or less constant in the PCB, but 3 weeks p.i. the density in the lungs increased up to 14 times to that in the PCB, whereas in the liver it decreased at the same time to a density similar to that in the PCB. In patent animals with adult worms delivering mf these were distributed as follows: 34·7% were calculated to be in the PCB; 24·4% were obtained by perfusion from the lungs and 22·0% from the liver; the rest were found in the kidneys (16·6%) and spleen (2·3%). In the lungs and the liver about 5/6 were associated with adherent cells, partly disintegrated or as fragments. In view of the fact that very few mf become disintegrated immediately after i.v. injection and also from their extremely long sojourn in the PCB, a low turnover rate of mf is presumed. The limited fecundity of the female adults combined with the 20 weeks median circulation time of injected mf in the PCB supports this view.
Contractile protein system in the asexual stages of the malaria parasite Plasmodium falciparum
Authors: Webb S. E. , Fowler R. E. , O'Shaughnessy C. , Pinder J. C. , Dluzewski A. R. , Gratzer W. B. , Bannister L. H. , Mitchell G. H. 
Published: June 2009

SUMMARYF-actin was detected in asexual-stage Plasmodium falciparum parasites by fluorescence microscopy of blood films stained with fluorescent phalloidin derivatives. F-actin was present at all stages of development and appeared diffusely distributed in trophic parasites, but merozoites stained strongly at the poles and peripheries. No filament bundles could be discerned. A similar distribution was obtained by immunofluorescence with 2 polyclonal anti-actin antibodies, one of which was directed against a peptide sequence present only in parasite actin (as inferred from the DNA sequence of the gene). A monoclonal anti-actin antibody stained very mature or rupturing schizonts but not immature parasites. Myosin was identified in immunoblots of parasite protein extracts by several monoclonal anti-skeletal muscle myosin antibodies, as well as by a polyclonal antiserum directed against a consensus conserved myosin sequence (IQ motif). The identity of the polypeptides recognized by these antibodies was confirmed by overlaying blots with biotinylated F-actin. The antiserum and one of the monoclonal antibodies were used in immunofluorescence studies and were found to stain all blood-stage parasites, with maximal intensity towards the poles of merozoites. Our results are consistent with the presence of an actomyosin motor system in the blood-stage malaria parasite.
Description of a simulation model for the population dynamics ofEimeria acervulinainfection in broilers
Authors: Henken A. M. , Ploeger H. W. , Graat E. A. M. , Carpenter T. E. 
Published: June 2009

SummaryA simulation model for the population dynamics ofEimeria acervulinainfection in broilers is presented. The model describes the development of the numbers of parasites in the various life-stages during the growing period of broilers and the empty house period between grow-outs. The model includes assumptions with respect to development of immunity toE. acervulinainfection and effects of application of anticoccidial drugs. The model consists of a set of difference equations that are solved numerically at 1 h intervals. Under constant conditions, an equilibrium level was reached after a few grow-outs during which infection always peaked around the 21st day in the growing period. Within a growing period, infection peaked earlier (later) than the 21st day in case initial numbers of sporulated oocysts were higher (lower) than the equilibrium number.
Characterization of Theileria parva which infects waterbuck (Kobus defassa)
Authors: Stagg D. A. , Bishop R. P. , Morzaria S. P. , Shaw M. K. , Wesonga D. , Orinda G. O. , Grootenhuis J. G. , Molyneux D. H. , Young A. S. 
Published: June 2009

SummaryTheileria-free waterbuck (Kobus defassa) born in captivity were successfully infected with Theileria parva sporozoites derived from ticks infected by feeding on African buffalo (Syncerus caffer). All waterbuck underwent mild infections with the development of sporadic schizont and piroplasm parasitosis when inoculated with sporozoite doses lethal to cattle. A carrier state of T. parva was demonstrated by feeding clean R. appendiculatus nymphs on two of these infected waterbuck. Tick batches from these waterbuck on 2 of 5 occasions transmitted lethal Theileria infections to cattle. In a separate experiment, waterbuck cells were infected and transformed in vitro by T. parva sporozoites derived from buffalo but not by cattle-derived T. parva (Muguga) sporozoites. Waterbuck cells infected in vitro with T. parva isolated from buffalo were inoculated into autologous waterbuck but no infections developed. Theileria parva isolates generated in this study from various sources were characterized using anti-T. parva schizont monoclonal antibodies (MAbs), and it was found that buffalo-derived and waterbuck-passaged isolates had different profiles. Species-specific synthetic oligonucleotide probes, restriction fragment length polymorphism (RFLP) analysis with cloned T. parva DNA probes, and DNA sequence analysis of the p67 sporozoite antigen gene confirmed that the waterbuck-passaged parasite was T. parva. The Tpr repetitive probe hybridization patterns from the waterbuck-passaged parasites were different from the other samples tested. The ribosomal genotype of the waterbuck-passaged T. parva was similar to that of cattle-derived T. parva Muguga. Analyses with both probes and MAbs suggested that a minor parasite population present within the T. parva 7014 buffalo- derived stock had been selected during waterbuck passage. A variable region of the p67 sporozoite antigen gene of the waterbuck-passaged T. parva was similar to that of cattle-derived T. parva stocks and different from that of buffalo- derived parasites. Based on these results, methods were suggested to confirm and quantitate the involvement of waterbuck in the epidemiology of cattle theileriosis.
Ultrastructural localization of pancreatic polypeptide- and FMRFamide immunoreactivities within the central nervous system of the nematode, Ascaris suum (Nematoda: Ascaroidea)
Authors: Brownlee D. J. A. , Brennan G. P. , Halton D. W. , Fairweather I. , Shaw C. 
Published: June 2009

SummaryA post-embedding immunogold technique has been used to examine the subcellular distribution of immunoreactivities to vertebrate pancreatic polypeptide (PP) and to the invertebrate peptide, FMRFamide within the central nervous system (CNS) of the nematode, Ascaris suum. Gold labelling of peptide was localized exclusively over dense-cored vesicles within nerve cell bodies, nerve axons and nerve terminals of the main ganglia and nerve cords in the CNS. Double-labelling of peptides demonstrated an apparent co-localization of PP and FMRFamide immunoreactivities in the same dense-cored vesicles, although populations of dense-cored vesicles that labelled solely for FMRFamide were also evident. Antigen preabsorption studies indicated little or no cross-reactivity between the two antisera.
Infection of dogs by Toxocara canis carried by flies
Authors: Pegg Elizabeth J. 
Published: June 2009

Attempts were made to infect Stomoxys calcitrans, Lucilia sericata and Musca domestica with embryonated eggs of Toxocara canis and Toxascaris leonina. Only Musca domestica was successfully infected with Toxocara canis eggs.Six Beagle pups were given anthelmintic treatment and infected flies were then fed to five of them. The five pups were examined at varying intervals, the sixth being used as a control. Four of the experimentally infected pups showed evidence post-mortem of having become infected with Toxocara canis by the ingestion of Musca domestica. Larvae of Toxocara canis were recovered from several tissues. Immature and adult forms were recovered from the intestinal contents. The results suggest that flies of Musca domestica are not only a source of infection to the dog, but that they may be of importance in the spread of toxocariasis in man.I would like to thank Professor A. O. Betts and Dr W. P. Beresford-Jones for their encouragement and helpful criticism and also Mr G. Yeoman and Mr B. C. Warren of Beecham Research Laboratories, Wheathampstead, for their assistance and for the supply of flies. I am also very grateful to Mr and Mrs D. Appleton, Carmarthenshire, Wales for their co-operation in treating and supplying the beagle pups.