bluuebunny/crossref_metadata_2025 huggingface dataset:
Schistosoma mansoni: DNA synthesis in males and females from mixed and single-sex infections
Authors: Den Hollander J. E. , Erasmus D. A.
Published: June 2009

The pattern of DNA synthesis in male and femaleSchistosoma mansonifrom mixed and single-sex infections in mice has been determined biochemically and autoradiographically using the incorporation of [3H]-thymidine as a specific marker of DNA synthesis. During early development (up to 35 days post-infection (p.i.)) adult males and females from mixed infections had a comparable specific activity of DNA. In males, from 35 days p.i. onwards, the specific activity of DNA decreased rapidly to become significantly different from that observed in females. In single-sex infections DNA synthesis in females was depressed compared to that observed in males from single-sex infections and was also significantly different (P≼ 0·01) from DNA synthesis in females from mixed infections. There was no significant difference in DNA synthesis between males from single or mixed infections. DNA synthesis in both sexes was found to be sensitive to hydroxyurea treatment, the inhibition in sexually mature females being approximately 75% and in males approximately 45%. Autoradiography using both light microscope and electron microscope techniques revealed that the testes and ovary had labelled cells. In male schistosomes the only other labelled cells were small undifferentiated cells found scattered through the tissues. In females the vitelline gland had large numbers of densely labelled nuclei within Stage 1 vitelline cells, as well as numerous small undifferentiated cells.
Schistosoma mansoni: further studies of the interaction between schistosomula and granulocyte-derived cationic proteinsin vitro
Authors: McLaren Diane J. , Peterson C. G. B. , Venge Per
Published: June 2009

Purified eosinophil and neutrophil cationic proteins isolated from the lysosomal secretion granules of human leucocytes have been tested for cytotoxic capacity against lung-stage schistosomula ofSchistosoma mansoni in vitro. Eosinophil cationic protein (ECP) caused paralysis but not death at high concentration; this effect was reversible and involved no gross pathological manifestations. Eosinophil protein X (EPX) and neutrophil cationic protein (NCP) were highly toxic at concentrations of 10−5mol/1, and induced paralysis at sublethal concentrations. These two proteins exerted their cidal effect principally against the subtegumental musculature and internal tissues of the parasite rather than against the surface syncytium and tegumental outer membrane. ECP and NCP were shown to bind to lung worms at paralysing concentrations, but this binding occurred independently of the charge of the parasite surface. Of several control proteins tested, only protamine was capable of destroying lung-stage parasites; the manifestations of damage were different, however, from those induced by the granulocyte-derived proteins. Parallel assays demonstrated that EPX also possessed cytotoxic capacity against newly transformed schistosomula, but it was less efficient than ECP in this respect. The data are discussed in relation to potential post-skin mechanisms of challenge attrition in the immunized host.
Hymenolepis diminuta: the mechanism of egg hatching
Authors: Holmes S. D. , Fairweather I.
Published: June 2009

The fine structure and histochemistry of the envelopes surrounding the mature oncosphere of Hymenolepis diminuta have been investigated by transmission electron microscopy and light microscope observations of JB-4 embedded material. The fate of these envelopes during the hatching sequence in vitro has been followed by phase-contrast and scanning electron microscopy. Hatching is considered to comprise 4 stages. Stage 1 involves the mechanical breakage and removal of the shell and the outer cytoplasmic layer of the inner envelope; Stage 2 the activation of the oncosphere and the swelling of the gelatinous layer of the inner envelope; and Stage 3 the digestion and rupture of the embryophore. This is accomplished both by secretions from the penetration gland and by the action of external digestive enzymes, together with hook activity. Trypsin is more effective than amylase in digesting the embryophore. Stage 4 involves the enzymatic weakening of the gelatinous layer which helps the oncosphere to tear itself free with its hooks. Amylase is more effective than trypsin in attacking the gelatinous layer. On emergence from the gelatinous layer, the oncosphere is still enveloped by the ‘oncospheral membrane’, although this covering is soon lost. Once activated, the oncosphere is capable of completing the hatching sequence by itself, without the addition of enzymes. This process is a lengthy one, however, taking up to 2 h, and the expenditure of its glandular and energy reserves makes successful gut penetration by the oncosphere unlikely.
The use of faecal egg counts for estimating worm burdens in sheep infected with Haemonchus contortus
Authors: Coadwell W. J. , Ward P. F. V.
Published: June 2009

Clun forest sheep, worm-free from birth, were given a single dose of 20000 infective larvae of Haemonchus contortus. The total number of eggs/day in the faeces was recorded for 21 infections and data on population size, sex ratio and individual worm development were collected from 76 sheep. The female to male ratio was 1·28±0·07 (s.E.). The relation between increase in worm size and uterine egg content was linear. The number of eggs present in the uteri was found to be an accurate measure of eggs passed. It was shown that the daily faecal egg output is related to total parasite weight and is not a measure of the number of individuals present.
Scanning electron microscopic study of the tegumental surface of adult Schistosoma mekongi
Authors: Vongpayabal P. , Sobhon P. , Upatham E. S. , Wanichanon C. , Mitranond V. , Tanphaichitr N. , Tumbel V. E. C.
Published: June 2009

The surface topography of the tegument of adult Schistosoma mekongi was studied by scanning electron microscopy (SEM). In comparison to other species of human schistosomes the male tegument lacks tubercles and, except in the gynecophoral canal, also lacks spines; instead the surface is composed chiefly of trabeculae of highly perforated ridges which give it the ‘spongy’ appearance. In addition, there are 3 kinds of papillae interspersed on the surface among the ridges. The first is a doughnut-shaped papilla with a central crater which is most abundant on the ventral surface of the anterior part, on the floor of the gynecophoral canal and on the dorsal-lateral aspect of the tail. The second is a pleomorphic papilla with irregular shape and size, which is scattered throughout the dorso-lateral aspect of the middle part of the body. The third type of papilla has a uniform hemispherical shape, possesses a cilium projecting from its apex and probably corresponds to the ‘sensory papilla’ found in other species. The tegument of the female differs from that of the male by having numerous short spines over the whole surface; however, the pleomorphic papillae are much fewer in number and the ridges are much less developed than those of the male tegument; complex trabeculae are absent.
Schistosoma mansoni: scanning electron microscopy of schistosomula, adults and eggs grown in vitro
Authors: Basch P. F. , Basch Natalicia
Published: June 2009

Development of surface topography of cultured Schistosoma mansoni was followed in the cercariae, newly transformed and older schistosomula, and adults. Comparison with surface features of schistosomes from animal infections revealed no apparent differences in tegumental folding or morphogenesis, spines, sensory structures, or other components. Eggs produced by worm pairs grown in vitro were grossly abnormal, usually composed of loosely packed vitelline granules and lacking a shell.
Food intake and body weight changes in mice infected with metacestodes of Taenia crassiceps
Authors: Crompton D. W. T. , Arnold S. E. , Walters D. E. , Whitfield P. J.
Published: June 2009

General nutritional effects on female CFLP mice harbouring larval Taenia crassiceps were investigated using groups of mice fed ad libitum on purified diets containing 2%, 4%, 8% and 16% (w/w) protein respectively. When uninfected and infected mice were compared over an experimental period of 20 weeks, it was established that a significantly higher proportion of uninfected mice survived the course of the experiment than infected mice. There was no evidence of the presence of the parasites having any effect on the overall food intake of the mice. Infected mice, however, were found to be significantly heavier, on a fresh weight basis, than their uninfected partners, but the pattern was reversed when the dry weights of mouse carcasses were compared following the removal of parasites. In general, more parasite tissue was recovered from mice feeding on the higher protein diets (8% and 16%).
The schistosomulum surface antigens ofSchistosoma haematobium
Authors: Simpson A. J. G. , Knight M. , Hagan P. , Hodgson J. , Wilkins H. A. , Smithers S. R.
Published: June 2009

Surface antigens ofSchistosoma haematobiumwere identified by125I-surface labelling of schistosomula followed by immunoprecipitation of the solubilized, labelled surfaces. The major antigens, after electrophoresis, formed a continuous smear corresponding to a molecular weight in the range 35–24000; in addition, a 17000 antigen was also identified. These surface antigens, in contrast to somatic antigens, were species-specific, as judged by immunoprecipitation with human anti-S. mansoniserum and serum from mice vaccinated with highly irradiatedS. mansonicercariae.S. haematobiumsurface antigens, however, were recognized to some extent by serum from mice chronically infected withS. mansoni. It is suggested that this cross-reactivity may reflect the heterologous immunity demonstrated experimentally between these two species, whilst the species-specificity of vaccine sera to surface antigens may mirror the highly specific immunity induced by vaccination.
Interspecific effects betweenMoniliformis(Acanthocephala),Hymenolepis(Cestoda) andNippostrongylus(Nematoda) in the laboratory rat
Authors: Holland Celia
Published: June 2009

Rats harbouring 35-day-old primary infections ofMoniliformis moniliformisandHymenolepis diminutawere inoculated with equal doses ofNippostrongylus brasiliensisand were autopsied 10 days later. Significant reductions were found in the dry weight ofMoniliformisandHymenolepisand in the numbers ofNippostrongylusrecovered compared with single infections. Similarly, in infections with two parasites, the numbers ofNippostrongyluswere reduced when concurrent withMoniliformisand the dry weights ofMoniliformisandHymenolepisdecreased in the presence of each other. A comparison of the concurrent infections themselves revealed thatMoniliformisweighed significantly less in the presence ofHymenolepisthan in the three parasite infections. Parasite interactions and their possible mechanism are discussed and comparisons are made with the relevant single infection for each parasite.
Studies with Eimeria acervulina and E. mivati: pathogenicity and cross-immunity
Authors: Norton C. C. , Joyner L. P.
Published: June 2009

Pathogenic effects caused by graded doses of recent isolates of Eimeria acervulina, E. mivati and a new isolate, thought at first to be E. mitis, were compared. Cross-immunity studies were conducted with 3 strains of E. acervulina and 2 strains of E. mivati, together with the new isolate. The results showed marked similarities between E. mivati and the new isolate and clear distinctions between these and E. acervulina. E. mivati produced scattered petechiae but did not form discrete lesions in the intestine comparable to those seen with E. acervulina. Endogenous stages of E. mivati were most numerous in the lower small intestine and proximal caeca. The ratio of villus height to total mucosal thickness in the lower intestine was reduced. Similar changes caused by E. acervulina were seen in the anterior intestine only.
Infection dynamics of Diplostomum spathaceum cercariae and parasite-induced mortality of fish hosts
Authors: Brassard P. , Rau M. E. , Curtis M. A.
Published: June 2009

The present study deals with the infection dynamics of Diplostomum spathaceum and with the direct parasite-associated mortality of its experimental fish host, guppies (Lebistes reticulatis) and brook trout (Salvelinus fontinalis). The relationship between exposure density and cercarial penetration of the hosts is essentially linear. There is a significant decrease in the proportion of penetrating cercariae that establish themselves in the fish lens at a high exposure density. The host death rate increases exponentially with parasite burden in both guppies and brook trout.
Comparison of surface iodination methods by electron microscopic autoradiography applied in vitro to different life-stages ofDipetalonema vitae(Filarioidea)
Authors: Baschong W. , Rudin W.
Published: June 2009

Different stages ofDipetalonema viteae(males, females, microfilariae, and 3rd-stage larvae) have been iodinatedin vitrounder physiological conditions by chloroglycoluril, lactoperoxidase or chloramine T. The concentrations of the catalysts were correlated with the viability of the worms. Localization of the label with the different iodination methods had been visualized by electron microscopical autoradiography. Chloroglycoluril-mediated iodination is predominantly localized on the filarial cuticle. Lactoperoxidase-catalysed iodination is less specific and chloramine T catalyses iodination in a gradient decreasing from the cuticle to inner structures. It is necessary to visualize the labelling by electron microscopical autoradiography prior to biochemical and immunological experiments to avoid the extraction of structures iodinated by leakage of the catalyst into sub-cuticular regions.
Pathogenicity of the coccidium Eimeria crandallis in laboratory lambs
Authors: Catchpole Janet , Gregory M. W.
Published: June 2009

Ten colostrum-deprived, coccidia-free lambs were reared artificially in indoor cages. At 4 weeks of age they were allocated to 5 groups of 2: Groups 1–3 received 104 105 and 106 sporulated oocysts of Eimeria erandallis/lamb respectively, each as a single inoculum. Group 4 lambs received daily doses increasing over a 4-week period. Groups 1–3 showed diarrhoea and weight loss from about day 14, followed by slow recovery from about day 30. The diarrhoea was accompanied by a wave of oocyst output and a reduction in serum albumin and plasma alkaline phosphatase activity. One lamb in group 4 died of an unrelated condition on day 15; the other showed no clinical effect of the oocyst inoculations and its oocyst output was related only to the first week or two of inoculation. Lambs in Group I showed no clinical effect or oocyst output following challenge with 106 oocysts on day 28. E. crandallis showed high pathogenicity and immunogenicity. Its pathogenicity was not closely related to infecting dose within the range 104–106.
Passive transfer of resistance and the site of immune-dependent elimination of the challenge infection in rats vaccinated with highly irradiated cercarie ofSchistosoma mansoni
Authors: Ford M. J. , Bickle Q. D. , Taylor M. G. , Andrews B. J.
Published: June 2009

The immune-dependent elimination of a challenge infection in rats vaccinated with highly-irradiated cercarriae ofSchistosoma mansoniwas analysed by passive transfer of serum, recovery of the challenge from the lungs and liver and by transferring lung-stage schistosomula. Recipients of serum from rats immunized with either unirradiated, 20 or 40 krad.irradiated cercariae, most of which die in the liver, lungs and skin, respectively, were equally resistant if the serum was injected on the day of infection or 5–7 days after infection. In addition, vaccinated rat serum transferred to mice and vaccinated rabbit serum transferred to rats conferred comparable protection when injected on day 0 or 5 days after infection of the recipents. This apparent susceptibility of the lung schistosomula to immune attack was confirmed by challenging 20 or 40 krad.-irradiated cercariae vaccinated rats with lung-stage schistosomula derived either from mice or rats. All the detectable attrition of a cercarial challenge in vaccinated rats occurred between 7 and 10 days post-challenge, before the parasites reached the liver. Since there was no evidence of damage or attrition in the skin or lungs before day 7 it was concluted that immune-dependent elimination occurred rapidly following a ‘window of sensitivity’ coinciding with the migration of the parasites from the lungs to the liver.
Studies on the pathophysiology of chronic ovine haemonchosis in Merino and Scottish Blackface lambs
Authors: Abbott E. M. , Parkins J. J. , Holmes P. H.
Published: June 2009

An experiment was conducted to examine, under laboratory conditions, the pathophysiology of chronic ovine haemonchosis. In the present study, groups of Merino and Scottish Blackface lambs were maintained on a low plane of nutrition and infected with 50 Haemonchus contortus larvae/kg live weight. The parasitized lambs along with respective breed controls were examined over a 27-week period. In addition to the body weight, haematological and parasitological parameters, erythrokinetic, metabolic, digestibility and nitrogen balance studies were conducted in the early stages of the infection. The results demonstrated that a low level of infection with H. contortus in lambs on a poor plane of nutrition caused the development of a normochromic normocytic anaemia which was associated with a modest but significant increase in abomasal blood loss and slightly elevated erythropoiesis in both breeds relative to the controls. The level of anaemia, hypoproteinaemia and pathophysiological changes were more marked in the Merino lambs and they also had higher faecal egg counts than the Blackface lambs.
An ultrastructural study of developing stages of exo-erythrocytic Plasmodium berghei in rat hepatocytes
Authors: Meis J. F. G. M. , Verhave J. P. , Jap P. H. K. , Hess F. , Meuwissen J. H. E. T.
Published: June 2009

The ultrastructure of immature exo-erythrocytic forms of Plasmodium berghei in rat hepatocytes was studied at stages between 25 and 51 h of development. A new method was successfully applied to localize the parasites in a small portion of the liver by temporary ligature of blood vessels to the majority of the liver, and from the spleen and the pancreas. Nuclear profiles appeared to be part of a highly lobed nuclear reticulum. Peripheral vesiculation and vacuolization of the cytoplasm was increasingly prominent and ushered in the formation of pseudocytomeres. Spacing between host- and parasite-derived membranes could first be observed after 43 h of development. In general, organellar development was found to follow closely that described for plasmodial oocysts.
The influence of the H-2 complex on responses to infection bySchistosoma mansoniin mice
Authors: Jones Janet T. , Mccaffery D. M. , Kusel J. R.
Published: June 2009

In order to determine whether a given H-2 haplotype has similar effects on responses to schistosomiasis mansoni on different genetic backgrounds, mice of 2 pairs of congenic strains (H-2band H-2kon BALB/c and C57BL/10 backgrounds) were infected. Worm burdens, mortality, splenomegaly, tissue and faecal egg counts, and antibody titres to worm and egg antigens were measured. The genetic background had a major effect on the genesis of splenomegaly, on the deposition of eggs in the spleen, the maximum faecal egg count, the antibody titre to egg and worm antigens and the rate of generation of antibody response. The H-2 haplotype was shown to consistently influence the maximum faecal egg count and the antibody titres. Worm burden was not influenced by genetic differences between strains and mortality differences were not significant. The data presented here indicate that the effect of the major histocompatibility complex on responses to infection is greatly influenced by the genetic background on which it is expressed.
Feeding behaviour ofGlossina morsitans morsitansinfected withTrypanosoma vivax, T. congolenseorT. brucei
Authors: Moloo S. K.
Published: June 2009

The feeding behaviour ofGlossina morsitans morsitansinfected withTrypanosoma vivax, T. congolenseorT. bruceiwas studied and compared with that of uninfected control tsetse. The following parameters were measured. (1) Mean number of feeds taken in 20 consecutive days; (2) mean rate of blood meal intake in μg/sec of the total days fed; (3) mean weight of blood meal intake/day of the total days fed; (4) mean total blood meal engorgement in 20 days; (5) mean number of probes/day of the days fed; (6) mean frequency of the multiple probe feeds and (7) mean number of pre-feeding probes of the multiple probe feeds. Evidence was found to suggest that the rosettes ofT. vivaxandT. congolensein the proboscis, and colonies ofT. bruceiparasites in the salivary glands, did not significantly alter the feeding behaviour of the vector.
The impact of host nutrition on gastrointestinal helminth populations
Authors: Bundy D. A. P. , Golden M. H. N.
Published: June 2009

Malnutrition and helminth infection are amongst the most prevalent chronic conditions affecting human health globally. It is estimated that parasitic helminths infect more than 1 billion people, and that more than 2 million clinical cases occur each year (Peters, 1978; Walsh, 1984). Estimates of the incidence of clinical malnutrition suggest that between 5 and 8 million cases occur annually. In many parts of the developing world malnutrition and infection conjointly are the most serious health problem in children, acting as primary or more often as secondary factors in mortality (Puffer & Serrano, 1973). The impact on health is exacerbated because both conditions are chronic, are most common in growing children and, most importantly, tend to occur together in the same individuals (Pawlowski, 1984; Chandra & Newberne, 1977).
Echinococcus granulosus: the effects of praziquantel, in vivo and in vitro, on the ultrastructure of equine strain murine cysts
Authors: Richards K. Sylvia , Morris D. L. , Daniels D. , Riley E. M.
Published: June 2009

Praziquantel (500 mg/kg) administered orally to BALB/c mice with secondary equine E. granulosus daily for 21, 30 or 30 + 30 days without the drug resulted in the majority of cysts, using bench criteria of turgidity and eosin exclusion, being assessed as ‘alive’. Ultrastructural examination of 54 of these ‘alive’ cysts did not support this conclusion. They all showed increased vesiculation of the germinal layer leading, in many, to the loss of its integrity. Increased mitochondrial numbers occurred frequently. The longer drug treatments appeared to have greater effects on the germinal layer of ‘alive’ cysts and there was no detectable re-establishment of structural organization within 30 days after drug withdrawal. Subjectively, there was no substantial difference between cysts from 4-month and 9-month infections or between affected peritoneal and hepatic cysts. Tissue from collapsed cysts was necrotic. Peak serum levels of praziquantel (6430–6136 μg/l) occurred 5–10 min after drug administration (500 mg/kg) and dropped rapidly to less than 10 μg/l at 3 h. In an in vitro study at praziquantel concentrations of 1000 and 5000 μg/l over a 10-day period, most cysts were judged ‘alive’ by bench criteria but showed ultrastructurally a time- and concentration-dependent loss of integrity identical to that seen in vivo. Turgidity and eosin exclusion therefore underestimate the effect of praziquantel and the results indicate that in vitro experiments can fulfil a legitimate preliminary role in a hydatid chemotherapy programme.
Evidence for population self-regulation, reproductive competition and arrhenotoky in a thelastomatid nematode of cockroaches
Authors: Zervos S.
Published: June 2009

Experimental infection of adultDrymaplaneta variegataShelford, 1909 (Blattodea) with known numbers of eggs ofProtrellus dixoniZervos, 1987 (Nematoda: Thelastomatidae) showed that each infrapopulation was regulated by a density-dependent and sex-dependent reduction in infection intensity with infrapopulation age. This reduction was not equal in initial speed or intensity between the sexes (reduction in number of males was faster) and led to infrapopulations with never more than a single adult male, 1–8 (usually 1–3) adult females and 0–28 juvenile females. In structure, these laboratory-produced infrapopulations resembled those in field-collected hosts. Parasite-mediated chemical interference competition is suggested as the cause of infrapopulation regulation.Per capitaegg production was greater in uncrowded worms which suggests that self-regulation benefits those nematodes that survive competition. Unmated females produced male offspring only (probably by arrhenotokous parthenogenesis). Only females that occurred with a male produced females although some also produced males; such females may avoid insemination or prevent fertilization of some or all eggs. Female offspring probably result from amphimixis.
Immunization of cattle using varying infective doses of Theileria parva lawrencei sporozoites derived from an African buffalo (Syncerus caffer) and treatment with buparvaquone
Authors: Mutugi J. J. , Young A. S. , Maritim A. C. , Linyonyi A. , Mbogo S. K. , Leitch B. L.
Published: June 2009

A Theileria parva lawrencei isolate in the form of a sporozoite stabilate, derived by feeding clean Rhipicephalus appendiculatus nymphal ticks on an African buffalo (Syncerus caffer) captured in the Laikipia District, Kenya, was inoculated into groups of cattle at dilutions between 100 and 10-3. Groups of 3 cattle infected with 1 ml inocula at 100, 10-1 and 10-2 dilutions were treated with 2·5 mg/kg body weight of buparvaquone on day 0 and similar groups were left untreated to act as controls. An additional group, given 100 dilution of the stabilate, was treated with buparvaquone on day 8 post-inoculation. It was found that all control cattle inoculated with the stabilate at dilutions between 100 and 10-2 became infected, but only 2 out of 3 cattle developed patent infections at 10-3 dilution. All 3 control cattle receiving 100 dilution died of theileriosis, 2 at 10-1 and 10-2 dilutions, and 1 at 10-3 dilution died. Buparvaquone treatment on day 0 at 100 dilution resulted in the survival of 2 of 3 cattle and all the cattle at 10-1 and 10-2 dilutions. All the surviving cattle eventually developed a significant serological response against T. parva in the indirect fluorescent antibody test, except 1 in the 10-3 dilution group, and were immune to homologous challenge when tested 3 months later with a lethal inoculum of stabilate, except 2 cattle in the 10-3 dilution group. As a result of a theileriosis problem at about day 60 after inoculation in 2 cattle given 10-2 dilution of stabilate and buparvaquone treatment on day 0, an additional 5 cattle were given 10-2 dilution of stabilate and developed a good immunity after buparvaquone treatment. None was shown to develop the carrier state. Treatment with buparvaquone on day 8 after infection with 100 dilution of stabilate was not successful since 2 died. The stabilate used was shown to produce reproducible infection in cattle at different dilutions.
Infection of bovine T cell clones with genotypically distinctTheileria parvaparasites and analysis of their cell surface phenotype
Authors: Conrad P. A. , Baldwin C. L. , Brown W. C. , Sohanpal B. , Dolan T. T. , Goddeeris B. M. , Demartini J. C. , Ole-Moiyoi O. K.
Published: June 2009

Different stocks and stabilates within a stock ofTheileriaparvawere analysed for genotypic differences and for their effect on the expression of host cell surface antigens following infection of BoT8+T lymphocyte clones. The parasites were characterizedin vitroby hybridization ofT. parva- specific DNA probes to Southern blots of endonuclease-digested DNA from the infected T cell clones. Phenotypic changes in the host lymphoblastoid cells before and after infection were examined using lineage-specific monoclonal antibodies which reacted with the differentiation antigens BoT2, BoT4, Bo6, BoT8 and a null cell marker on bovine T cells. Expression of Class I and Class II major histocompatibility complex (MHC) antigens on the cell populations was also assessed. Results of this study indicate that genotypically different parasites exist among and withinT. parvastabilates and that the expression of Bo6, BoT8 and the null cell marker was differentially altered by infection with parasites from different stocks or from different stabilates of the same stock. Expression of Class II antigens was significantly increased after infection. Moreover, clones that were derived from the same cell line but had genotypically distinctT. parvaparasites, also showed differences in expression of Bo6 and BoT8 and the null cell marker.
Mesocestoides corti: parameters of infection in CBA/Ca mice and the effect of introducing a concomitant trematode infection
Authors: Chernin J. , McLaren Diane J. , Morinan A. , Jamieson B. N.
Published: June 2009

CBA/Ca mice infected with the tetrathyridia of Mesocestoides corti were exposed to Schistosoma mansoni cercariae either simultaneously, or at varying intervals after the initial M. corti infection. Cohorts were infected with either parasite alone. The dual infected mice and the mice harbouring M. corti alone were significantly heavier than either naive controls or mice carrying the S. mansoni infection only. The livers and spleens from dual infection mice were also found to be significantly heavier than those from other groups. Free M. corti tetrathyridia were reduced in number in the peritoneal cavity of dual infected mice, as compared with mice harbouring a single infection. Furthermore, the intensity of the initial M. corti infection, as measured by the number of capsules surrounding parasites in the liver, was reduced when the mice experienced an S. mansoni infection 21 days later. The mice which were exposed to M. corti only exhibited more mast cells and eosinophils around encapsulated tetrathyridia in the liver than did dual infection mice, while cells surrounding S. mansoni egg granulomas in the liver were significantly increased in dual infection mice. An increase in serum alkaline phosphatase levels was detected in both the mice receiving the dual infection and the mice with the S. mansoni only infection, but not in mice harbouring M. corti alone.
The development of exo-erythrocytic schizonts ofPlasmodium berghei in vitrofrom gamma-irradiated and non-irradiated sporozoites: a study using confocal laser scanning microscopy
Authors: Sinden R. E. , Couchman A. , Suhrbier A. , Marsh F. , Winger L. , Ranawaka G.
Published: June 2009

Confocal scanning laser microscopy has been used to study the distribution of antigens expressed by the liver stages ofPlasmodium bergheiin cultured hepatoma cells. The 3-dimensional images obtained of intact parasites clearly show complex patterns of antigen expression not apparent when using conventional IFAT or immunoelectron microscopy. A liver-stage specific antigen (Pbl 1) was shown to be confined to the parasitophorous vacuole; the vacuole has extensive diverticulae extending into the host cell. Small parasites were detected for the first time in ‘mature’ cultures. These did not represent a distinct population, but the ‘tail’ of a broad continuum of parasite sizes. Irradiated sporozoites produce a transient population of slow-growing parasites which express a very limited range of antigensde novoin the invaded hepatoma cell. A comparison of the reactivity of text-abstract EE parasites with anti-circumsporozoite antibody and with anti-Pbl 1 suggests that the former reagent may reliably be used to identify sporozoites invading host cells, but should not be used to determine the number of parasites that successfully undergo intrahepatic development. Anti-Pbl-1 indicates on 33% of invaded sporozoites identified by anti-CSP subsequently differentiate.
The influence of individual, social group and household factors on the distribution of Ascaris lumbricoides within a community and implications for control strategies
Authors: Haswell-Elkins Melissa , Elkins D. , Anderson R. M.
Published: June 2009

The distribution of Ascaris lumbricoides within a community was examined at an initial mass anthelmintic treatment programme (January 1984) and following an 11-month period of reinfection (November 1984). Similar patterns of the negative binomial parameter k (an inverse measure of parasite aggregation) and the proportion of parasites within the most heavily infected quartile of the community were recorded at the two dates. The pattern of parasite aggregation within individuals, measured by parameter k, appears to be a stable characteristic of this host-parasite relationship. Significant variation in the intensity of infection was observed between households in the community. The number of family members living in the house strongly influenced the mean Ascaris burden and proportion of relatively heavy infections within adults and children. This finding suggests that the density of people in a house positively influences the frequency of exposure to infective stages of Ascaris, which in turn plays a major role in determining which individuals will harbour heavy infections. Positive correlations were recorded between the initial and reinfection burdens of individuals, relative to others in the community. The correlations were strongest in the youngest and oldest age groups and were more frequently significant among age-stratified groups of females, compared to males. A comparative examination of hypothetical treatment strategies suggests that for Ascaris infections in this community, targetting age groups with anthelmintic treatment would probably be more cost-effective in the long term in reducing the abundance of this parasite than selective treatment of individually identified heavy infections.
The effects of genetic exchange on variable antigen expression in Trypanosoma brucei
Authors: Turner C. M. R. , Aslam N. , Smith E. , Buchanan N. , Tait A.
Published: June 2009

The inheritance of variant surface antigens in Trypanosoma brucei has been determined by identifying variable antigen types (VATs) in each of two cloned parental stocks and then examining the presence and abundance of these VATs in hybrid progeny produced when these stocks undergo genetic exchange during co-transmission through tsetse flies. Nine VATs have been identified from the repertoire of the parental stock STIB 247L and 5 VATs have been identified from the parental stock STIB 386AA; the identified VATs were exclusive to each stock. Their inheritance was elucidated using two assays. In the first, repertoire antisera (RAS) containing antibody specificities to many different VATs were raised in rabbits to the 2 parental stocks and 6 progeny clones. The presence of VAT-specific antibodies in these RAS was then determined by antibody-dependent complement-mediated lysis. In the second assay, the 2 parental stocks and 4 hybrid progeny clones were each independently transmitted through tsetse flies and VATs observed using VAT-specific antisera in indirect immunofluorescence of metacyclic trypanosomes and in bloodstream forms of fly-bitten mice. The results from both assays showed that (1) both metacyclic- and bloodstream-VATs were inherited into the progeny, (2) each hybrid progeny clone contained some VATs from both parents, (3) hybrids did not express all the VATs from either parent, (4) there was little apparent pattern as to which VATs had been inherited and which had not and (5) the VAT repertoires of the hybrid progeny appeared to be larger than those of the parents. In addition, two results indicated that control of VAT expression remains unaltered after genetic exchange. Firstly, the immunofluorescence results showed that VATs present in hybrid trypanosomes were expressed at the same stage during an infection and at approximately the same prevalence as in the parent. Secondly, a double-labelling experiment using direct immunofluorescence indicated that individual hybrid trypanosomes did not generally simultaneously express more than one VAT. Taken together, these results demonstrate that recombinant VAT repertoires are created when trypanosomes undergo genetic exchange and that genetic exchange is a mechanism whereby the generation of new serodemes can occur.
Role of the nematode surface coat in the adhesion of Clavibacter sp. to Anguina funesta and Anguina tritici
Authors: McClure M. A. , Spiegel Y.
Published: June 2009

Clavibacter sp. (syn. Corynebacterium rathayi) adhered to both Anguina funesta (syn. Anguina agrostis) and Anguina tritici, but differences in the nature of adhesion were noted. Similar patterns of binding of the bacteria and of anti-wheat germ agglutinin antibody initially led us to believe that the mechanism of bacterial adhesion was related to the presence of wheat-germ agglutinin (WGA) on the outer cuticle of both species of nematodes and its complementary carbohydrate on the bacterial capsule. However, treatment of either species of nematode with sodium metaperiodate inhibited bacterial adhesion but not the binding of anti-WGA antibody. Bacterial adhesion, therefore, is not mediated by WGA on the nematodes' surface. Moreover, differences in patterns of bacterial adhesion to Anguina species, both before and after treatments with NaCl and detergents, suggest basic interspecific differences in the nature of adhesion. Electron microscopy confirmed the contribution of the nematodes' cuticular surface coat (SC) to the process of adhesion, but it is still not clear how the SC interacts with the bacterial capsule or which of its components are involved. While complete removal of the SC with periodate prevented bacterial adhesion, juveniles that naturally resisted bacterial adhesion did not lack a SC. One explanation could be that the SC of individuals, to which bacteria do not adhere naturally, lacks crucial components that cannot be defined by conventional EM.
Toxicity of cyclosporin A (CsA) against developmental stages of Schistosoma mansoni in mice
Authors: Munro G. H. , McLaren D. J.
Published: June 2009

It has been shown elsewhere that the immunosuppressive drug cyclosporin A (CsA) exerts profound schistosomicidal activity when given to infected mice via a multiple administration regime. We show here that a single treatment regime also effects significant reductions in worm burden. Moreover, drug efficacy is maintained at CsA concentrations shown to be subimmunosuppressive in other systems. Subcutaneous treatment effected higher levels of schistosomicidal activity than intraperitoneal or oral treatment, irrespective of whether the drug was given prior to or during infection. Topical application of CsA to the skin site of cercarial penetration, prior to infection resulted in no reduction in worm burden. Systemic release of CsA from a slowly adsorbed, oil-based drug-vehicle combination effected greater levels of killing than when CsA was dissolved in an aqueous drug vehicle. All developmental stages of Schistosoma mansoni were susceptible to killing by a single dose of CsA but, in the case of liver-stage worms, an increased concentration of drug and a longer period between treatment and portal perfusion were needed for killing to be measurable as a reduction in worm numbers.
Polyclonal activation of B lymphocytes during experimental infection withSchistosoma mansoni
Authors: Lopes L. M. , Pereira M. A. C. , Gerken S. E. , Vaz N.
Published: June 2009

A significant polyclonal activation of B lymphocytes was observed during experimental infection of C57BL/10J mice withSchistosoma mansoni. The isotypic pattern of this expansion, assessed by the Protein-A plaque-forming cell method, was compared with and found to differ from those occurring after infection byTrypanosoma cruzior injection of bacterial LPS. In the infection ofS. mansonian early expansion of most immunoglobulin isotypes occurs together with a late, sustained expansion of IgG1-secreting cells. High levels of polyclonal B cell activation were observed after adoptive transfer of spleen cells from infected mice to isogenic recipients pre-treated with hydroxyurea.
Honey bee mortality due to tracheal mite parasitism
Authors: Royce L. A. , Rossignol P. A.
Published: June 2009

We demonstrate, by truncating the expected negative binomial distribution, that the tracheal mite parasite, Acarapis woodi, causes mortality in the Europen honey bee, Apis mellifera, but, that this mortality can be documented only during periods of low mite densities (mites per bee). At high mite densities, this technique no longer reveals mite-induced mortality. We suggest that this paradox results from a reduction in the mortality threshold at high mite densities, concealing mortality from our truncation procedures. Longitudinal comparisons of hive and forager bee cohorts, nevertheless, suggests mortality at all levels of infestation. We propose that persistent parasitism overcomes a colony's ability to compensate for losses, leading to its sudden decline and death.
Oxytetracycline inhibition of mitochondrial protein synthesis in bovine lymphocytes infected withTheileria parvaor stimulated by mitogen
Authors: Spooner P. R.
Published: June 2009

Oxytetracycline (OTC) significantly inhibited cytochrome c oxidase activity in bovine lymphocytes infected withTheileria parvaand in uninfected mitogen-stimulated lymphocytes. The inhibitory effect was detectedin vitrowithin 24 h of treatment with drug concentrations as low as 1 µg/ml. Following mitogen stimulation of lymphocytes, concentrations of 3 and 10 µg/ml OTC completely inhibited an increase in cytochrome c oxidase activity for 48–72 h. This inhibitory activity was considered to be due to a direct effect on lymphoblast mitochondrial protein synthesis. As a consequence, adenosine triphosphate activity was significantly reduced in lymphocytes stimulated either by infection withT. parvasporozoites or by mitogen and then treated with OTC. The results also indicated that parasite mitochondrial protein synthesis was inhibited by OTC. The activity of OTC reported in this study could explain the suppression of disease following ‘infection and treatment’ immunization against East Coast fever and thein vitrodrug-inhibition of schizont development.
Effects of three anthelmintics on the tegument ofHymenolepis fraterna(Cestoda)
Authors: Stoitsova S. R. , Gorchilova L. N. , Daněk J.
Published: June 2009

Thein vivoeffects of the anthelmintics taenifugin, VÚFB 14170 and VÚFB 15269 on the tegument ofHymenolepis fraternahave been examined by SEM, TEM and cytochemistry. The drugs were given toH. fraterna-infected mice on the 14th day post-infection in a single oral dose of 150, 200 and 200 mg/kg, respectively. By 72 h post-treatment, the drug-induced pathomorphological changes in the tegument indicated that all three drugs had a significant effect. Changes were most pronounced on the brush border and in the intercellular material. On the apical surface, there was blebbing as well as accumulation of membrane fragments over the microthrix tips and erosion of the brush border. The intercellular material was changed in structure, showing increased electron density in some areas and oedema of the intercellular spaces in other areas. There were also fractures of the tegument of variable depth, sometimes reaching to the parenchyma. These results suggest altered tegumental integrity and, occasionally, complete disruption of the selective permeability barrier created by the normal tegument. This suggestion is further supported by the penetration of ruthenium red into some tegumental areas and its distribution into the intercellular spaces, down to the parenchyma. The intrategumental lysosomes also appeared to be significantly activated. There was evidence of autophagy in both distal cytoplasm and tegumental cells. Mature and gravid proglottides were more susceptible to drug damage than those in the anterior strobila and neck.
The anti-leishmanial activity of dipeptide esters onLeishmania amazonensisamastigotes
Authors: Ramazeilles C. , Juliano L. , Chagas J. R. , Rabinovitch M.
Published: June 2009

L-Amino acid esters, such as L-Leu-OMe, killLeishmania amazonensisamastigotes by a mechanism which appears to involve ester hydrolysis by cysteine proteinases located in the parasite megasomes. We have examined the killing of isolated amastigotes by L-dipeptide esters and derived some structure-activity correlations. Toxicity of the compounds for the parasites was measured by a tetrazolium (MTT) reduction assay. The results show that active dipeptide esters contained at least I hydrophobic amino acid (Leu, Ile, Val, Phe or Trp). The activity of homodipeptide methyl esters depended on the nature of the amino acid, as indicated by the following series: Phe-Phe-OMe < Val-Val-OMe < Leu-Leu-OMe < Trp-Trp-OMe < Ile-Ile-OMe. The nature of the amino acids in Leu-X-OMe and X-Leu-OMe was relatively unimportant when X was Phe, Trp or Val. However, when X was Ala or Gly, Leu-X-OMe was several-fold more active than X-Leu-OMe.
Dynamic changes of DNA sequences in Schistosoma mansoni in the course of development
Authors: Nara T. , Iwamura Y. , Tanaka M. , Irie Y. , Yasuraoka K.
Published: June 2009

Deletion and/or amplification of DNA sequences in Schistosoma mansoni were demonstrated by Southern blot analysis. Total cellular DNAs and genomic clones derived from S. mansoni miracidia, adult males and females were used as probes. EndonucleaseBamHI-restricted DNAs from miracidia, adult males and females of both S. mansoni and S. japonicum were reacted to each probe. Hybridization with a total cellular DNA from S. mansoni miracidia as a probe showed elimination of signals in S. mansoni adults. On the other hand, blot analysis using a total cellular DNA from S. mansoni adult males as a probe revealed elimination of hybridization signals in S. mansoni miracidia.Hybridization with a clone SmE15 DNA from S. mansoni miracidia as a probe showed no signal in the DNAs from 5. mansoni adults, indicating these sequences deleted in adults. Hybridization experiments using the probes SmF25 and SmM51 which are 13 and 2-2 kb fragments cloned from S. mansoni adult females and males respectively, demonstrated no signal to DNA from S. mansoni miracidia.Our data suggested the existence of stage-specific DNA sequences in 5. mansoni. We propose a model for multiple-step rearrangement of DNA sequences in S. mansoni during the course of development.
Models to assess the potential ofCapillaria hepaticato control population outbreaks of house mice
Authors: McCallum H. I. , Singleton G. R.
Published: June 2009

Population outbreaks of house mice (Mus domesticus) occur periodically in the wheatlands of southeastern Australia. This paper uses mathematical models to assist in the evaluation of the potential of a nematode,Capillaria hepatica, as a biological control agent to reduce the severity of these ‘plagues’.C. hepaticais unique amongst helminths of mammals in that its eggs are released only upon the death of an infected host. The major goal of the modelling in this paper is to determine the impact of this feature on the population dynamics of the host-parasite interaction. Simple differential equation models are used to examine the general properties of the system and determine which population parameters are most crucial to the outcome of the interaction. These models are supplemented by age-structured models which investigate the initial behaviour of the system after introduction of the parasite. The necessity of host death for transmission is a strongly destabilizing factor, suggesting thatC. hepaticacannot regulate most populations stably in the absence of strong resource limitation, although it has the potential to depress mouse populations below infection-free levels. AlthoughC. hepaticainfluences mouse fecundity at lower burdens than it affects mortality, the age-structured models show that parasite-induced host death cannot be neglected. Because transmission requires host death, the parasite life-cycle operates on a time-scale similar to that of the hosts, and introduction of the parasite as early as possible in the development period of an outbreak will therefore be necessary to achieve substantial reductions in plague intensity.