bluuebunny/crossref_metadata_2025 huggingface dataset:
Reproductive potential of Gyrodactylus bullatarudis (Monogenea) on guppies (Poecilia reticulata)
Authors: Scott Marilyn E.
Published: June 2009

Two simple experiments were undertaken using the viviparous ectoparasite, Gyrodactylus bullatarudis, and laboratory-reared guppies, Poecilia reticulata, whereby detailed records of the number and temporal sequence of all births and the age at death were obtained for flukes on isolated guppies. Gyrodactylus bullatarudis has an average fecundity of 1·68 offspring during its expected life-span of 4·20 days. The instantaneous birth rate is independent of generation but dependent on age. The first offspring is born approximately 1 day after the birth of the parent and subsequent offspring are born at 2–2·5 day intervals. The average instantancous birth rate (under given experimental conditions) is 0.43/parasite/day. The death rate increases exponentially with the age of the fluke and has an average value of 0.24/parasite/day. A simple deterministic model incorporating age structure and an age-dependent death rate was found to provide a good fit to the observed exponential increase in G. bullatarudis numbers. The variability observed in this host–parasite system was found to be largely a function of chance, as shown by Monte Carlo simulations of stochastic birth–death processes.
The specificity of purine base and nucleoside uptake in promastigotes ofLeishmania braziliensis panamensis
Authors: Hansen B. D. , Perez-Arbelo J. , Walkony J. F. , Hendricks L. D.
Published: June 2009

Promastigotes ofLeishmania braziliensis panamensisabsorbed the purines adenine, hypoxanthine, adenosine and inosine by a combination of diffusion and mediated components. When the uptake rates for these substrates were corrected for diffusion and compared, the purine bases adenine and hypoxanthine were transported at a significantly slower rate than the purine nucleosides adenosine and inosine. Competitive interactions among those purines tested confirmed the presence of mediated and diffusion components and suggested that three transport loci may be operating (Fig. 6). The first transport locus, designated Locus 1, transported inosine, Locus 2, the purine bases hypoxanthine and adenine and Locus 3, adenosine. In addition, adenine and hypoxanthine inhibited the uptake of one another competitively. A comparison of Kivalues derived from double reciprocal plots of labelled hypoxanthine and adenine uptake in the presence of the unlabelled substrates as inhibitors suggested that adenine has a greater affinity for the transport locus.
IgG response of rats and humans to the released products of schistosomula ofSchistosoma mansoni
Authors: Verwaerde Claudie , Auriault C. , Damonneville Martine , Grzych J.-M. , Pierce R. , Capron A.
Published: June 2009

The participation of products released fromSchistosoma mansonischistosomula (SRP-A) in the IgG antibody response of infected Brown-Norway rats and infected humans has been studied using immunoprecipitation with various antigenic preparations and inin vitrocytotoxicity assays. A large number of SRP-A molecules with a wide range of molecular weights was recognized by infected rat and human sera. Anti-SRP-A antibodies appeared in rat sera from day 28 after infection. In infected humans, a variable pattern of SRP-A recognition was observed between individuals. IgG antibodies obtained by immunization of rats with SRP-A without addition of adjuvants reacted with 3 major schistosomula surface proteins with molecular weights of 38, 32 and 21 kDa. These latter molecules were also revealed strongly by infected rat sera. Moreover, these antibodies were able to kill schistosomulain vitroin the presence of complement or eosinophils.
Lethality of intestinal tissue extracts from Eimeria-infected chickens
Authors: McKenzie M. E. , Johnson Joyce , Long P. L.
Published: June 2009

Evidence exists that lethal activity is associated with extracts from Eimeria tenella-infected caecal tissues. We examined tissues of the small intestine infected with other species of Eimeria for a similar lethal activity. Extracts were prepared from intestinal tissues of chickens infected with either E. acervulina, E. brunetti, E. maxima, E. mitis or E. necatrix. Appropriate control extracts from tissues of non-infected chickens were also prepared. Intravenous injection of the extracts into healthy chickens showed that lethality of infected tissue extracts was higher than control extracts and was independent of the site of infection within the intestine. Comparison of the lethality of caecal extracts from chickens infected with embryo-adapted or parent lines of E. tenella showed that lethality was independent of the recognized pathogenic characteristics of the lines. Also, it was demonstrated that lethal activity is associated with extracts of tissues containing massive numbers of arrested and non-arrested sporozoites and early trophozoites.
Plasmodium brasilianum in the common marmoset Callithrix jacchus
Authors: Wedderburn Nina , Mitchell G. H. , Davies D. R.
Published: June 2009

Chronic quartan malarial infection has been established in the common marmoset (Callithrix jacchius). Plasniodium brasilianunm from a douroucouli monkey (Aotus trivirgatus) was used to infect splenectomized twin animals, passed to an intact animal, and then to 4 other intact adults, 2 pairs of twins. In 2 of the 4 latter animals there was continuing patency with parasitaemias of ≤0·5% parasitized erythrocytes for 30 weeks. The other 2 had lower initial levels of paraaitaemia; in 1 of these parasitaemias remained low or subpatent. All marmosets developed lymphocytosis. One animal became ill 30 weeks after infection with anaemia, weight loss and mild proteinurea, the other 3 remained well. Histological examination showed minor changes in the kidneys; spleens of infected animals showed marked follicular hyperplasia and phagocytosis of pigment. The livers showed sinusoidal hyper cellularity and pigment deposition and in splenectomized animals, a marked lymphoid follicular hyperplasia in the portal tracts.
Passive transfer of resistance to mice with sera from rabbits, rats or mice vaccinated with ultraviolet-attenuated cercariae ofSchistosoma japonicum
Authors: Moloney N. A. , Hinchcliffe P. , Webbe G.
Published: June 2009

All serum transfers from donor rats or rabbits given single or multiple vaccinations of ultraviolet (u.v.)-attenuatedSchistosoma japonicumcercariae conferred significant resistance against challenge to mice. Donors given 5 vaccinations, however, produced the most effective sera; rat sera giving up to 88% protection and rabbit sera up to 80%. This protective effect was species-specific and titratable. Sera from vaccinated rabbits and rats were were most effective when transferred to mice 2 h before challenge, but became progressively less effective when transferred with increasing time after challenge. These sera had no efficacy when given 6 days after challenge. Thus, sera from vaccinated rabbits and rats were effective against the early stage of migration, but did not necessarily have to act in the skin as all serum transfers were as effective against intraperitoneal as percutaneous challenge. By contrast, serum from multiply vaccinated mice had little or no protective effect when transferred to mice before challenge, but conferred 62% resistance when transferred 5 days after challenge. Further, there was an additive protective effect when vaccinated rat and mouse sera were given in combination at their optimum transfer times (days 0 and +5, respectively). Thus, there appears to be a stage-specific immune response induced by vaccination depending upon whether the vaccinated hosts are truly permissive or not. Vaccinated rats and rabbits respond to the early phase of migration and vaccinated mice make protective responses against the lung phase of migration.
The influence of Hymenolepis diminuta on the survival and fecundity of the intermediate host, Tribolium confusum
Authors: Keymer Anne E.
Published: June 2009

An experimental study of the effects of parasitism by H. diminuta on the intermediate host, Tribolium confusum, is described. No density- dependent constraints on parasite establishment within individual hosts are evident, although a reduction in cysticercoid size at high parasite burdens is demonstrated. The relationship between parasite burden, host mortality and host fecundity is investigated. Host mortality is linearly related to parasite burden, whereas the relationship between parasite burden and host fecundity is non-linear. There is no difference in viability between eggs from infected and uninfected females. The generative causes of these effects are not investigated experimentally, although it is postulated that survival is related to the degree of damage to the midgut wall caused by parasite penetration, and fecundity to the biomass of parasites harboured by the host. The significance of these effects is discussed in relation to the overall dynamics of the host-parasite association.
Culture of microsporidia from invertebrates in vertebrate cells
Authors: Smith Judith E. , Barker Rosalind J. , Lai P. F.
Published: June 2009

Nosema algerae and N. eurytremae were successfully cultured in embryonic rat brain, Xenopus XTC-6 and Chang liver cells, and in embryonic rat brain and XTC-6 cells respectively. No parasites grew in cultures incubated at 38 °C but development took place in cells incubated at 34 °C and 27 °C. Increased levels of infections of the cultured cells were achieved by centrifugation of the spores on to the cells. The level of infection was also related to the type of medium used for hatching the spores, modifies NMRI giving better results than Leibowitz L15, and to the interval between adding the spores to the cell cultures and centrifugation.
Distribution of exposed and hidden carbohydrates ofSchistosoma mansoniadult worms demonstrated by selective binding of fluorochrome-conjugated lectins
Authors: Linder E. , Huldt G.
Published: June 2009

The distribution of exposed and hidden lectin-binding glycoconjugates in adultSchistosoma mansoniworms was studied. Fluorochrome-conjugated lectins were allowed to react both with intact worms and with frozen sections of worms. The results show a selective reactivity of lectins with tegumental surface structures, the intestine, eggs and basement membranes. Strong binding of wheat germ agglutinin (WGA) was seen to the exposed surface of intact worms. Peanut agglutinin (PNA),Ricinus communisagglutinin (RCA) and concanavalin A (Con A) gave a weaker reaction. There was a preferential affinity of PNA and RCA to the spikes covering the tubercles of male worms whereas Con A gave a more uniform staining pattern. Internal structures exposed in frozen sections of worms gave distinct staining reactions. Binding sites for Con A were widely distributed throughout the worm. PNA produced a more selective binding and was the only lectin staining basement membranes as distinct structures. There was a strong selective staining of the gut with soybean agglutinin (SBA) and RCA. Eggs seen in large quantities inside female parasites reacted strongly with SBA and PNA and less intensely with RCA and WGA. The observed selectivity of lectin binding may reflect physiological function. The results may be important as a basis for using lectin affinity-chromatography for purification and characterization of worm constituents
Purification ofTrypanosoma bruceivariable surface glycoproteins: analysis of degradation occurring during isolation
Authors: Barbet A. F. , McGuire T. C.
Published: June 2009

Trypanosoma bruceivariable surface glycoproteins (VSGs), isolated from some antigenic types of trypanosomes, degraded during isolation. We show that this degradation occurred immediately after breakage of the organism, presumably because of liberation of internal enzymes, and resulted in heterogeneity of isolated VSGs with respect to charge and/or molecular weight. Degradation and consequent heterogeneity of these VSGs could be abolished by releasing VSG from the trypanosome surface without breakage of the organism. The method was a modification of an incubation and shaking procedure initially described forTrypanosoma congolense(Reinwald, Rautenberg & Risse, 1979). WaTat 1.11 VSG released by this method and isolated, had a molecular weight (mol. wt) of 63000 and bound to a heterologous anti-VSG serum. VSG isolated from the same trypanosomes following breakage of organisms was of lower molecular weight. One such WaTat 1.11 VSG fragment of 42000 mol. wt, did not bind to the heterologous anti-VSG serum and therefore lacked cross-reacting antigenic determinants present in the 63000 mol. wt VSG
The host–parasite relationships in normal and protein-malnourished cotton rats infected withLitomosoides carinii(Nematoda: Filarioidea)
Authors: Storey D. M.
Published: June 2009

A total of 120 young cotton rats were fedad libitumfor 10 weeks on either synthetic diets containing 2·5, 5, 10 or 15% casein or on a stock breeding diet containing 20% crude protein. Half of the animals in each group were infected with the filarial nematodeLitomosoides cariniiand the food intake and body weight of each animal was measured. There was a trend towards increased food consumption in protein-deficient cotton rats and this was increased further in infected animals; however, differences between groups were not significant. Low protein diets reduced the rate of growth of uninfected and infected cotton rats; filarial infection intensified these adverse effects of under-nutrition and increased the number of rats which died in the lowest protein group. Protein deficiency had little effect on the number ofL. cariniiwhich developed, although fewer parasites became established in cotton rats fed on a 2·5% diet than in those fed on a 10% diet. Parasites developing in protein-deficient animals were shorter than those developing in well-fed ones and embryo-genesis was retarded in female worms from protein-deficient animals. The onset of patency was retarded in protein-deficient animals and the microfilaraemia which developed subsequently was lower up to 120 days post-infection.
Melanization and encapsulation in Aedes aegypti and Aedes togoi in response to parasitization by a filarioid nematode (Breinlia booliati)
Authors: Ho B.C. , Yap E.-H. , Singh M.
Published: June 2009

In Aedes aegypti (Singapore strain), a refractory host, there was a marked progressive decline of developing larvae of Breinlia booliati during the incubation period. However, in Aedes togoi, a susceptible host, the filarial larvae developed normally and the number of larvae remained constant throughout the incubation period. Encapsulation and melanization of B. booliati larvae in Ae. aegypti and Ae. togoi were studied. Ae. togoi occasionally mounted a defence reaction to the infection. In Ae. aegypti, various stages of filarial larvae were frequently affected by the defence mechanisms of the host, and a relatively large number of melanized larvae were recovered in dissections throughout the incubation period. The process of melanization is described and the relationship between melanization and haemocytes of mosquitoes is discussed. Haemocytes of the mosquito host appeared to be involved in the encapsulation of filarial larvae, as evidenced by adherence of cells to the cuticle of the larvae and the formation of a translucent, gelatinous envelope which contained intact cells, necrotic cells, spaces and numerous whitish granules. The possible involvement of a humoral reaction in bringing about the degeneration and retardation of the filarial larvae is discussed.
Niche segregation and sugar transport capacity of the tegument in digenean flukes
Authors: Uglem G. L. , Lewis M. C. , Larson O. R.
Published: June 2009

Digenean flukes can be broadly classified into three basic groups according to their location within the host: (1) the lumen of the alimentary canal or associated organ, (2) body cavity or tissue and (3) external surfaces. We selected three species of Proterometra that represent these basic groups and tested their capacities for cutaneous transport of glucose. Facilitated diffusion is the type of transport system in the tegument of P. edneyi, which lives in the gut of its host. An activetransport system is present in P. dickermani, the tissue-dwelling species. No cutaneous system for transporting glucose is present in the ectoparasitic P. macrostoma. The known capacities for tegumental sugar transport in other digeneans are correlated with similar habitats. Such associations involving unrelated as well as closely related species suggest that the niche biology of digeneans involves evolutionary specializations of the tegument for absorbing sugar.
Dose-dependent relationships between Nippostrongylus brasiliensis populations and rat food intake
Authors: Ovington K. S.
Published: June 2009

The pattern of daily food intake of well-nourished rats infected with Nippostrongylus brasiliensis included 2 distinct phases when food intake was much less than that of uninfected controls (days 0–4 and days 6–10 p.1.). These phases were separated by a period (days 4–6) of still reduced but relatively constant food intake. From day 10 p.i. food intake increased so that between days 12 and 17 infected rats ate more than uninfected controls. In each of the phases of reduced food intake there was a threshold dose above which food intake was further decreased as dose increased. In contrast to the obvious relationship between food intake and dose, food intake could not easily be related to the size of the adult Nipposirongylus population, as judged by egg and worm counts. The relationship appears to be complicated by host variability in susceptibility to infection and to the pathological effects of infection. Effects of N. brasiliensis on the daily pattern of food intake can be explained with respect to stages in the development of the parasite and host responses directed against the adult worms.
Topography and Ultrastructure of the tegument of adultSchistosoma mekongi
Authors: Sobhon P. , Upatham E. S. , McLaren Diane J.
Published: June 2009

The tegument of adultSchistosoma mekongihas been studied by both scanning and transmission electron microscopy. The gross surface topography of the parasite resembles that ofS. japonicum, in that branched ridges, microvilli and sensory papillae predominate; such characteristics distinguish these two species from the non-oriental schistosomes. A unique feature ofS. mekongi, however, is the numerous pleomorphic protruberances which are concentrated particularly on the middle three-fourths of the body surface. Transmission electron microscopy has revealed that these protruberances enclose bundles of microfilaments which appear to insert into the tegumental outer membrane. The microfilaments are suggested to have a supportive or stabilizing function, and may compensate for the absence of more typical crystalline spines. The tegumental outer membrane is typically heptalaminate in section, while the basal membrane infoldings are surrounded by concentrations of mitochondria. Three types of tegumental inclusion bodies have been recognized. Discoid bodies and membraneous bodies are morphologically identical to those described in all other schistosome species, except that the latter inclusions have been seen connected to each other and to the tegumental outer membrane by unique channels lined with trilaminate membrane. The third inclusion takes the form of spherical, lucent vesicles containing membrane fragments; these may represent the remains of spent membraneous bodies.
Running responses ofTrichinella spiralis-infected CD-1 mice
Authors: Rau M. E. , Putter L.
Published: June 2009

Male CD-1 mice inoculated by gavage with 400 larvae ofTrichinella spiralisexhibited an increased latency of the wall-seeking response as well as a decline in running speed and the distance travelled to the first stop when compared with normal controls or animals inoculated with only 100 larvae. Doses of 200 larvae of this parasite affected running speed and distance travelled but not the advent of the running response. Such changes in behaviour may reduce the competitive fitness of the host and render it more susceptible to predation.
Pairing and aggregation of Amblosoma suwaense (Trematoda: Brachylaimidae) metacercariae in vitro and partial characterization of lipids involved in chemo-attraction
Authors: Fried B. , Robinson G. A.
Published: June 2009

Histochemical and thin-layer chromatographic (t.l.c.) analyses were made on neutral lipids in the free (unencysted) metacercariae of Amblosoma suwaense (Brachylaimidae). As determined by t.l.c. the major neutral lipid fractions in metacercariae removed directly from Campeloma decisum snails were free sterols and sterol esters. Metacercariae incubated for 1 h at 37±1° C in sterile Locke's solution released mainly sterol esters and a lesser amount of free sterols into the medium. As determined by Oil Red O (ORO) staining, metacercariae accumulated neutral lipid in the intestinal caeca during incubation and the excretory system was ORO negative. Behavioural studies showed that metacereariae paired and aggregated in vitro and were attracted to lipophilic but not to hydrophilic worm products. Following t.l.c. preparative analysis it was demonstrated that metacercariae were attracted to sterol ester worm products but not to free sterol products.
Genes within the major histocompatibility complex of the guinea pig influence susceptibility toTrichostrongylus colubriformisinfection
Authors: Geczy A. F. , Rothwell T. L. W.
Published: June 2009

The influence of genes in the major histocompatibility complex (MHC) of the guinea pig on the susceptibility to infection with the parasitic nematodeTrichostrongylus colubriformiswas investigated. Back-cross analysis of 2 lines of guinea pigs suggests that genes that map in or near the I region of the guinea pig MHC influence susceptibility to infection by the parasite. However, other genes, possibily not linked to the guinea pig MHC, may also be required for the full expression of susceptibility.
Lernaeocera lusci(Copepoda: Pennellidae) on bib (Trisopterus luscus) from Southampton Water
Authors: Evans N. A. , Whitfield P. J. , Bamber R. N. , Espin P. M.
Published: June 2009

O-group bib,Trisopterus luscuscaught on the cooling water intake screens of Fawley Power Station in March and April 1982 were infected (prevalence = 34·8%; intensity = 1·65/infected fish) with adult females of the pennellid parasitic copepodLernaeocera lusci. The bib sample of 293 fish was divided, for analysis, into 5 length classes. In each of these the level of parasitization withL. lusciwas broadly similar and in all 5 classes the parasite population was over-dispersed. Of the living copepods onT. luscus, 93% possessed egg strings while the remaining 7% consisted of earlier developmental stages. The majority of the parasites were attached to gill arches and here they exhibited distinct microhabitat and orientation preferences. A 3–2–4–1 descending order of gill arch utilization was apparent and copepods were non-randomly distributed along the dorso-ventral axis of gill arches with medial and ventral sectors being more heavily used than dorsal ones. An analysis was carried out on the body and egg string wet weights of parasites removed from fish harbouring different parasite densities. As copepod density increased neither the mean parasite body weight nor egg string weight altered significantly. Length/weight relationships of uninfected and infected fish were remarkably similar and thus provided no evidence thatL. luscihas a marked effect on the condition of O-groupT. luscus. The study demonstrated a significant positive association between infection withL. lusciand heavy infections with metacercarial cysts ofCryptocotyle lingua.
Immunochemical analysis of surface membrane antigens on erythrocytes infected with non-cloned SICA[ + ] or cloned SICA[ − ]Plasmodium knowlesi
Authors: Howard R. J. , Barnwell J. W.
Published: June 2009

The SICA[ − ] or non-agglutinable phenotype ofPlasmodium knowlesischizont-infected erythrocytes has been defined serologically but not biochemically. Similarly, non-cloned SICA[ + ] or agglutinable parasites have been shown serologically to express SICA or variant antigen(s) but the number and nature of such antigens have not been defined. Here we describe the immunochemical analysis of surface antigen expression on [125I]lactoperoxidase-labelled erythrocytes infected either with a SICA[ − ] elone or with non-cloned SICA[ + ] parasites using the methods developed for identification of variant antigens with cloned SICA[ + ] parasites. No125I-labelled antigens in the size range Mr190000–225000 were specifically immunoprecipitated from erythrocytes infected with the SICA[ − ] elone, even using homologous antisera produced by multiple infections or immunizations. Further, no125I-labelled proteins of this size were seen in detergent extracts of the SICA[ −] parasites that were not also seen with uninfected cells. We conclude that the SICA[ − ] phenotype reflects the absence of a variant antigen at the erythrocyte surface, as predicted by the serological assays. In contrast, with the non-cloned SICA[ + ] parasites, a complex group of proteins, Mr195000–225000, was identified by [125I]lactoperoxidase labelling of intact infected erythrocytes. These proteins are SICA antigens since they not only share the characteristic detergent solubility properties and size range of SICA antigens identified previously with SICA[ + ] clones, but they were only immunoprecipitated by antisera which reacted specifically with the surface of infected erythrocytes. Agglutinating sera immunoprecipitated several of these125I-labelled antigens. Sera specific for clones derived from this non-cloned SICA[ + ] population failed to agglutinate, but did react by indirect immunofluorescence with 10–16% of infected cells. These sera specifically immunoprecipitated single, quantitatively minor125I-labelled antigens in this size range. The results suggest that a population of non-cloned SICA[+] parasites contains at least 10 different variant-antigen phenotypes. Indirect immunofluorescence was also performed against a non-cloned SICA[ + ] population derived by antigenic variation of a SICA[ + ] clonein vivo. The variant population contained at least 3 antigenically distinct SICA phenotypes, indicating that antigenic variation of clones may produce populations as antigenically heterogenous as antigenic variation of uncloned lines. It is therefore likely that natural malaria isolates contain a large number of different variant antigens.
Comparison of immune responses between high and low responder strains of mice in the concomitant immunity and vaccine models of resistance toSchistosoma mansoni
Authors: James Stephanie L. , Cheever A. W.
Published: June 2009

Mice of the inbred P strain fail to develop significant resistance to challengeSchistosoma mansoniinfection at 6 weeks after either low-grade primary infection or vaccination with attenuated homologous parasites, in contrast to other strains such as C57B1/6, and thus provide a model for comparison of potential immune resistance mechanisms in low versus high responder animals. In this study, the antigen-specific cellular responses found to correlate with resistance in these strains were delayed cutaneous hypersensitivity, production of macrophage activating lymphokine and macrophage larvicidal activity, all of which were greater in infected or vaccinated C57B1/6 mice than in similarly immunized but non-resistant P mice. Humoral responses correlating with resistance were IgM reactivity to schistosomula surface antigens in both infected and vaccinated animals, as well as both IgM and IgG reactivity to soluble schistosome antigens in infected mice. Immune responses that showed no relationship with resistance included IgG reactivity to larval surface antigens and immediate hypersensitivity to soluble worm antigens. In infected mice, neither granuloma size nor extent of hepatic fibrosis correlated positively with resistance to challenge infection. Thus, similarities exist between patterns of resistance and immune response at this early time after immunization with either viable or attenuated parasites. These observations suggest that common immune effector mechanisms could be involved, with activated macrophages playing a central role in resistance.
Studies on the invasion of Notocotylus attenuatus (Notocotylidae: Digenea) into its snail host Lymnaea peregra: the contents of the fully embryonated egg
Authors: Murrills R. J. , Reader T. A. J. , Southgate V. R.
Published: June 2009

The fully embryonated egg of Notocotylus attenuatus is shown to contain a sporocyst, an opercular cord and apparently 2 cells which are situated outside the sporocyst. One of these cells is rich in glycogen whereas the other contains a variety of inclusions. These contents are indicative of a truncated life-cycle which omits the miracidium, an observation as yet unique among the Digenea.
Fasciola hepatica in vitro: increased susceptibility to fasciolicides in a defined serum-free medium
Authors: Jenkins D. C. , Topley P. , Rapson E. B.
Published: June 2009

The cidal properties of some phenolic, halogenated diphenyl, salicylanilide, benzimidazole and diaminophenoxyalkane anthelmintics, against 6-week-old worms of Fasciola hepatica were assessed in vitro. In a conventional fluke culture medium containing RPMI 1640, supplemented with serum with or without rabbit erythrocytes or pink-ghosts, only the halogenated diphenyl and salicylanilide compounds showed activity at concentrations equal to or less than 100 μm. However, when basal, serum and cell-free RPMI 1640 was used, all compounds other than diamphenethide were highly active, their minimum lethal concentrations being some 25–125 times lower under these conditions. The inclusion of rabbit liver microsomes in the basal culture medium resulted in diamphenethide exhibiting cidal activity equivalent to that seen when its free-amine active metabolite was assayed. The possibility that the activity of many of these compounds was masked in vitro because of their serum binding properties is discussed. Recommendations are made that in vitro screens for new fasciolicides should be carried out in serum-free medium and that additional replicates containing mammalian liver microsomes and liver cytosolic extracts be included as means for the metabolic activation of certain otherwise undetectable prodrugs.
Peptidase in the plasma of mice infected withTrypanosoma brucei brucei
Authors: Knowles G. , Black S. J. , Whitelaw D. D.
Published: June 2009

The plasma of mice infected with pleomorphicTrypanosoma brucei bruceicontains a peptidase which has the same electrophoretic mobility on starch gels as a parasite peptidase. An enzyme with this electrophoretic mobility was not detected in the plasma of uninfected mice. The molecular weight of this enzyme in either parasite lysate or plasma from infected mice was approximately 40000 Da when assayed on a size exclusion column using high-performance liquid chromatography. The enzyme can cleave the dipeptides leu-ala, val-leu and pro-leu, but not the dipeptide phe-ala. The enzyme also cleaved the tripeptides tyr-tyr-tyr and leu-gly-gly. Another parasite peptidase which migrates on starch gels to a different position than the above-mentioned peptidase cleaved the dipeptides leu-ala, val-leu and pro-leu but could not cleave the tripeptides tyr-tyr-tyr or leu-gly-gly. Furthermore, incubation of this parasite peptidase with normal mouse plasma at 37 °C resulted in an apparent loss of detectable activity. It is postulated that the plasma of mice modifies either the charge or enzymic activity of this peptidase. We speculate that the parasite peptidase present in the plasma of mice infected withT. bruceicould contribute to pathogenesis.
Hatching and survival characteristics of Cyathocotyle bushiensis Khan 1962 (Digenea) eggs and miracidia
Authors: Ménard L. , Scott M. E.
Published: June 2009

Cyathocotyle bushiensis Khan 1962 is a digenean intestinal parasite of ducks that appears to be involved in seasonal mortality of the definitive host. Temperature dependence of egg hatching and miracidial survival at 25%C were experimentally investigated as part of a study on transmission of the larval stages. Maximum percentage of hatching was obtained at a temperature of 25%C, at which the average hatching time was 21·7 days. The average hatching time decreased linearly from 38·9 days to 9·8 days between 18 and 28%C. Eggs exposed to cold (4%C) prior to incubation at 25%C were significantly less successful in hatching than fresh eggs incubated at the same temperature. Their hatching percentage was much reduced and their average hatching time was increased. Similarly, eggs collected in late autumn (as opposed to summer) and incubated at 23%C had significantly lower hatching success and significantly increased average hatching time. At 25%C, the average life-span of the miracidia was 8·8 h. These results are compared with similar data from other digenean species and their significance is discussed in relation to transmission to the first intermediate host in climatic conditions prevalent in endemic areas.
A genetic comparison between natural and laboratory strains of Echinostoma (Trematoda) by isoenzymatic analysis
Authors: Voltz A. , Richard J. , Pesson B.
Published: June 2009

A comparative isoenzyme study between a natural population of Echinostoma caproni and 2 strains of E. caproni and E. togoensis, maintained for a long time in the laboratory led to the following conclusions. (1) The natural E. caproni population showed polymorphism of associated PGM and GPI genotypes. Some zymograms were identical to those of experimental strains. Allelic frequencies show that the natural population is panmictic according to the Hardy-Weinberg equilibrium. (2) The laboratory strains were monomorphic, and interbreeding produced double-heterozygous F1 progeny, identical to those of the natural population.
Comparative study on the infection rates of differentGlossinaspecies for East and West AfricanTrypanosoma vivaxstocks
Authors: Moloo S. K. , Kutuza S. B. , Desai J.
Published: June 2009

Teneral maleOlossina morsitans centralis, G. austeni, G. palpalis palpalis, G. p. gambiensis, G. fuscipes fuscipes, G. tachinoidesandG. brevipalpiswere fed on the flanks of Boran calves infected withTrypanosoma vivaxstock ILRAD 2241 isolated from a cow in Likoni, Kenya; stock ILRAD 2337 isolated from a cow in Galana, Kenya; stock ILRAD 1392 isolated from a cow in Nigeria; or, stock EATRO 1721 isolated fromG. m. submorsitansin Nigeria. The tsetse were fed on the infected hosts for 24 days and were then dissected to determine the infection rates. InG. m. centralisandG. brevipalpis, the mature infection rates ofT. vivaxfrom Kenya were 61·1 %, and 75·3% for ILRAD 2241, and 36·2% and 58·2% for ILRAD 2337, respectively. InG. austeniand in the fourpalpalisgroup of tsetse, the rates for these two stocks were very low and ranged from 0% inG. p. palpalisto 1·8% inG. austenifor ILRAD 2241 and from 0% inG. f. fuscipesto 5% inG. tachinoidesfor ILRAD 2337. In contrast, the hypopharyngeal infection rates ofT. vivaxfrom Nigeria were quite high in all the 7 tsetse species and sub-species. They ranged from 55·5% inG. austenito 919% inG. p. gambiensisfor ILRAD 1392, and from 71·4% inG. austeneito 97·1 % inG. brevipalpisfor EATRO 1721. It is suggested that successful establishment ofT. vivaxinfection in a particular tsetse species could depend on the biochemical characteristics of its attachment sites in the food canal and the efficiency of bloodstream trypomastigotes of a particularT. vivaxstock to attach to such sites and undergo complete development to meta-trypanosomes in the hypopharynx of the vector.
Modulation of the anti-phosphorylcholine immune response duringTrichinella spiralisinfections in mice
Authors: Ubeira F. M. , Leiro J. , Santamarina M. T. , Sanmartin-Duran M. L.
Published: June 2009

The nematodeTrichinella spiralisis able to modulate the antibody response, as measured by the plaque-forming cell (PFC) technique, to three thymus-dependent (TD) antigens: (1) a heterologous antigen unrelated to the parasite (sheep red blood cells (SRBC)); (2) an antigenic fraction, rich in phosphorylcholine (PC), obtained fromT. spiralis(FCpl) and (3) a heterologous antigen unrelated to the parasite, but sharing the PC epitope with the FCpl fraction (PC-KLH). During the life-cycle of the parasite in BCF1 mice, two opposing immunomodulating activities occur: (1) an immuno-potentiating activity in mice infected during the intestinal and larval migratory stages, for all three antigens, and (2) a carrier-specific immunosuppressive response in mice infected and immunized with the FCpl fraction during the muscle phase of the life-cycle. The anti-PC PFC response of these mice is dependent on the infection dose and decreases from day 35 post-infection (p.i.) until at least day 85 p.i.. The factor responsible for the stimulating effect observed during this stage is the presence of migratory larvae in the host. All the foregoing seems to indicate thatT. spiraliscan use specific suppression mechanisms to aid in its own survival.
Contributions of ascariasis to poor nutritional status in children from Chiriqui Province, Republic of Panama
Authors: Taren D. L. , Nesheim M. C. , Crompton D. W. T. , Holland Celia V. , Barbeau Irma , Rivera Gloria , Sanjur Diva , Tiffany Jean , Tucker Katherine
Published: June 2009

Relationships between ascariasis and lactose digestion and between ascariasis and food transit time from mouth to caecum were investigated in young children from Chiriqui Province, Republic of Panama. The breath hydrogen method was used in both studies.Ascaris-infected children showed a significantly poorer degree of lactose digestion following a test oral load than uninfected children. Recovery of the capacity of the children to digest lactose was still not fully complete for at least 3 weeks following anthelmintic treatment. On average, the mouth-to-caecum transit time was similar in infected and uninfected children, but among theAscaris-infected children the transit time tended to be shorter in relation to the intensity of infection. Evidence from a cross-sectional survey indicated that ascariasis was significantly associated with reduced plasma vitamin A and carotenoid concentrations. This relationship remained after controlling for a range of socio-economic variables.Ascaris-infected children were frequently found to have lower haematocrits and blood haemoglobin concentrations than uninfected children, but these relationships could not be attributed to ascariasis alone.
The muscle, nervous and excretory systems of the plerocercoid of Callitetrarhynchus gracilis (Rud., 1819) (Pintner 1931) (Cestoda: Trypanorhyncha) from Bermuda fishes
Authors: Rees F. Gwendolen
Published: June 2009

The plerocercoid of Callitetrarhynchus gracilis was found in the body cavity of 14 species of fishes from Bermuda. The scolex, having completed its development, continues to grow within the blastocyst. The two mobile bothridia possess lateral grooves containing backwardly directed spines. Rapid evagination of the proboscides is effected by two layers of contra-rotating spiral muscles in the walls of the proboscis bulbs. The proboscis retractor is protected from constriction, during contraction of the bulbs, by a rigid ring at the junction of bulb and sheath. Nine series of extrinsic muscles anchor the proboscis sheaths to the body wall and a ladder-like series of dorsal, ventral and lateral muscles anchors the bulbs to one another. The bulbar nerves arise from the lateral nerve cords and are joined by a series of central ring commissures along the length of the bulbs. Uniciliate sensilla occur on the scolex and glandular cells in the peduncle.
Invasion of mature and immature erythrocytes of CBA/Ca mice by a cloned line of Plasmodium chabaudi chabaudi
Authors: Jarra W. , Brown K. N.
Published: June 2009

During the early stages of the primary Plasmodium chabaudi chabaudi AS parasitaemia in CBA/Ca mice this parasite invaded normocytes, but as the parasitaemia developed increasing numbers of parasites were seen within reticulocytes. During and just after peak parasitaemia, as further parasite replication was controlled, the ‘crisis’ phase ensued, mice became increasingly anaemic and reticulocyte numbers were markedly increased. As the parasitaemia was resolved during crisis in excess of 25% of parasites had invaded reticulocytes. In phenylhydrazine-pretreated mice with artificially high reticulocyte levels and infected with P. c. chabaudi AS, normocyte/reticulocyte invasion occurred with equal frequency. No reduction in the infectivity of parasite populations developing in reticulocytes was observed.
Simulations of enhanced malaria transmission and host bias induced by modified vector blood location behaviour
Authors: Rossignol P. A. , Rossignol A. Mackay
Published: June 2009

Monte Carlo simulations were developed to assess the potential impact of parasite pathology on vector salivary function as well as of host haemostasis on transmission. Assuming that a proportion of desisting vectors switch host following failure to locate blood, we demonstrate three possible consequences: (1) infected vectors contact more hosts than non-infected hosts, (2) non-infected vectors are biased to infected hosts, independently of attraction, and (3) an exponential relationship exists between parasite load and transmission. We discuss possible epidemiological implications.
Leishmania mexicana mexicana: quantitative analysis of the intracellular cycle
Authors: Doyle P. S. , Engel J. C. , Gam A. A. , Dvorak J. A.
Published: June 2009

The complete intracellular cycle of theLeishmania mexicana mexicanaG. S. strain was quantified in human macrophages and in the mouse IC-21 macrophage line utilizing a culture system that allows the direct observation of individual intracellular parasites. A wide range of pre-replicative lag periods exists, implying that promastigotes may be in any phase of their DNA synthetic cycle when phagocytosed by the macrophage. Amastigotes replicated 2–3 times, after which the host cell died and liberated amastigotes that were taken up by other macrophages and continued to replicate. The mean amastigote population-doubling time in human macrophages (17.5 h) was not statistically different from promastigotes growing in axenic culture (16.4 h), but was nearly 2-fold less than amastigotes growing in mouse-derived IC-21 macrophages (33.7 h). These observations are markedly different from cover-glass culture assays ofLeishmania-macrophageinteractions and provide an unambiguous description of the intracellular cycle ofLeishmania mexicanamexicana.
A monoclonal antibody-derived antigen ofBabesia divergens: characterization and investigation of its ability to protect gerbils against virulent homologous challenge
Authors: Winger C. M. , Canning E. U. , Culverhouse J. D.
Published: June 2009

ABabesia divergensmerozoite antigen was purified by affinity chromatography using a monoclonal antibody. Silver staining of SDS-PAGE gels revealed 2 bands of Mr50–60 kDa and Mr24–29. It is proposed that the Mr24–29 kDa band represents the native protein and that it is complexed, perhaps as a dimer or perhaps to host protein to give the Mr50–60 kDa band. Peptide analysis of the antigen followed by Western blotting with the monoclonal antibody revealed only an Mr20–24 kDa band. After affinity purification the antigen was precipitated with acetone and inoculated subcutaneously, together with complete Freund's adjuvant, into gerbils. Two inoculations were given 3 weeks apart, after which the immunized animals and a group of control animals were challenged with 5 × parasitized red cells from a virulent microaerophilus stationary phase (MASP) culture of an homologous strain ofB. divergens. Parasitaemias rose rapidly in control animals and all were dead by the fifth day. Two of the vaccinated animals survived the challenge. Parasitaemias in the remaining two rose slowly but both animals succumbed on the seventh day. Western blotting of merozoites and of the purified antigen, using sera from the surviving animals showed strong reactivity with the Mr24–29 kDa band.
Variable generation of specific acquired resistance in CBA/Ca mice chronically infected with schistosomiasis mansoni
Authors: Delgado V. S. , Mclaren D. J.
Published: June 2009

Naive CBA/Ca mice and CBA/Ca mice infected 12 weeks previously with 20 normal cercariae ofSchistosoma mansoniwere challenged percutaneously with isotopically labelled parasites. Challenge worm migration was followed, in 5 separate experiments, by means of compressed organ autoradiography. In three experiments, 43.1 % of challenge parasites did not arrive in the lungs of infected mice on day 6 as compared to 7.7 % in naive controls, thereby indicating that pre-lung sites constitute the first barrier in resistance to reinfection. A further 15% of the challenge worm burden was lost in the lungs or en route to the liver in the immune animals, and portal perfusion revealed that 25.4% of the challenge was lost in the liver. Two other experiments revealed no comparable phases of pre-liver attrition however; instead resistance was only evident at final perfusion on days 28 or 35. These data reveal the variable generation of specific acquired immunity in mice harbouring a chronic schistosome infection and thus clarify current discrepancies in the literature. The results are discussed in relation to documented evidence for the nature of specific and non-specific immune mechanisms reported to operate at different sites in the infection model of schistosomiasis mansoni.
Effects of potential inhibitors on Brugia pahangi in vitro: macrofilaricidal action and inhibition of microfilarial production
Authors: Barker G. C. , Mercer J. G. , Svoboda J. A. , Thompson M. J. , Rees H. H. , Howells R. E.
Published: June 2009

A series of compounds that apparently disrupt hormonally regulated processes in insects have been examined for effects on the viability and microfilarial production of adult Brugia pahangi cultured in vitro. The azasteroids, 25-azacoprostane and 25-azacholestane, inhibited the production of microfilariae at 5 ppm, the former also exhibiting macrofilaricidal activity at this concentration. The brassinosteroids examined inhibited microfilarial production at 5 ppm but did not affect worm viability. Azadirachtin also proved to be a significant inhibitor of microfilarial release without effect on worm motility or viability. Of all the compounds tested, the non-steroidal amines appeared to be the most promising as potential filaricides, several of them proving to be macrofilaricidal at 1 ppm and affecting microfilarial production at even lower concentrations.
The population dynamics of acquired immunity to Heligmosomoides polygyrus in the laboratory mouse: strain, diet and exposure
Authors: Keymer A. E. , Tarlton A. B.
Published: June 2009

An experiment was designed to investigate aspects of the population dynamics of acquired immunity to Heligmosomoides polygyrus in laboratory mice. The influence of host strain (CBA or NIH), rate of exposure (5 or 40 L3/mouse/2 weeks) and diet (3 or 16% protein w/w) on the population dynamics of repeated infection and the response to a standard challenge infection were investigated. The time delay between the end of the period of repeated infection and the subsequent challenge (between 1 and 24 weeks) had no effect on worm recovery. The effects of both exposure and diet were significant and similar whether assessed on the basis of the dynamics of repeated infection or response to challenge: low rates of exposure and low dietary protein were both associated with low levels of acquired immunity. Mouse strain was the most important determinant of worm recovery after challenge, but had no significant effect on the degree to which parasite population growth was constrained by acquired immunity during repeated infection. It is suggested that both CBA and NIH mice raise immune responses which act on parasite survival, but that only NIH mice raise responses operative against larval establishment.