bluuebunny/crossref_metadata_2025 huggingface dataset:
Metabolic changes associated with the migration of the schistosomulum ofSchistosoma mansoniin the mammal host
Authors: Ruth Lawson J. , Wilson R. A.
Published: June 2009

A variety of measurements was made on small samples of schistosomula recovered from the skin, lungs and hepatic portal system of percutaneously infected mice, on the basis of which development could be divided into a migration and a growth phase. The density of schistosomula, estimated using a Ficoll gradient, was found not to vary significantly between Day 0 and Day 24 post-infection, having a mean value of 1·077. The reduced weight was measured by means of a Cartesian diver balance and used in conjunction with density to estimate the change in wet weight of schistosomula. Wet weight was found to decline slightly during the migration phase and to increase exponentially following arrival of schistosomula in the hepatic portal system. No change in nitrogen content was detected during migration but there was a rapid increase after arrival in the hepatic portal system. The rate of oxygen consumption, measured by Cartesian diver respirometer, declined significantly during migration and then increased exponentially after arrival of worms in the hepatic portal system. No change was detected in the lactic dehydrogenase activity of migrating worms but again, an exponential increase occurred after entry into the hepatic portal system. It was concluded that the migrating schistosomulum is in a semi-quiescent metabolic state, although it possesses the ability to take up nutrients and undergoes morphological changes. Growth is triggered by an unknown mechanism after arrival in the hepatic portal system. Examination of the various sets of data suggests that it is initiated between 10 and 11 days post-infection in the most advanced schistosomula.
Observations on the surface morphology of the ovarian balls ofMoniliformis(Acanthocephala)
Authors: Parshad V. R. , Crompton D. W. T. , Martin Jean
Published: June 2009

The surface morphology of fixed ovarian balls from femaleMoniliformis dubius, aged 12, 18, 26, 28, 42, 77, 105 and 118 days, has been examined by means of scanning electron microscopy. The appearance of the surface has been found to be variable between ovarian balls from worms of the same and different ages. Some parts of the surface are seen to possess micro-projections, cavities and ridges while other parts have the appearance of an irregular meshwork of fibres. Various protruding features have been observed to extend from the surfaces of the ovarian balls taken from the inseminated female worms. In most cases, the surfaces of the protruding features differ in appearance from the surrounding surfaces of the ovarian balls. Some of these features have been assumed to represent growing zygotes and developing eggs covered by the supporting syncytium of the ovarian ball. Single or several thread-like structures have been observed in association with the surfaces of ovarian balls taken from the inseminated female worms. At present, the thread-like structures are believed to be portions of spermatozoa. By means of light microscopy, preliminary observations have been made on what is considered to be the division process of ovarian balls taken from uninseminated and inseminated worms varying in age from 7 to 98 days.
Activation of prophenol oxidase in the liver flukeFasciola giganticaCobbold
Authors: Thangaraj T. , Nellaiappan K. , Ramalingam K.
Published: June 2009

Activation of prophenol oxidase ofFasciola giganticahas been demonstrated using biochemical and electrophoretic techniques. Based on the difference in the electrophoretic pattern of the proenzyme and activated enzyme, a probable mechanism of activation of the prophenol oxidase is suggested. A role for Mehlis' gland in the activation process is suggested. The significance of the results is discussed in the light of related studies in insects.
In vitro formation of ookinetes and functional maturity of Plasmodium berghei gametocytes
Authors: Janse C. J. , Mons B. , Rouwenhorst R. J. , van der Klooster P. F. J. , Overdulve J. P. , van der Kaay H. J.
Published: June 2009

In vitro formation of Plasmodium berghei ookinetes was studied. Gametocytes produced in vitro were obtained from heart and tail blood of Swiss mice and from blood removed from mosquitoes directly after feeding on these mice. In vitro produced gametocytes were obtained from short-term cultures of the erythrocytic stages of P. berghei. Reproducible ookinete production was obtained in medium RPMI 1640, pH 7°8–8°0, using in vivo and in vitro produced gametocytes. The morphology of developmental stages of ookinetes and degenerate forms at the light microscope level is described. More ookinetes were produced in medium RPMI 1640 compared to MEM and ookinete yield – defined as the ratio between the number of in vitro produced ookinetes/105 erythrocytes and the number of exflagellations/105 erythrocytes in the infected blood – increased with lower erythrocyte densities in the cultures within the range of dilutions tested. A linear relationship existed between gametocytaemia and the number of ookinetes produced. The methods for in vitro ookinete formation and for estimating ookinete yields enabled us to study aspects of functional maturity of gametocytes independent of mosquitoes. The numbers of exflagellating gametocytes and in vitro ookinete yields in tail blood corresponded with those in heart blood and blood ingested by mosquitoes, suggesting a random distribution of functionally mature gametocytes within the vertebrate host.
The metabolism of xenobiotic compounds byHymenolepis diminuta(Cestoda: Cyclophyllidea)
Authors: Munir Widad A. , Barrett J.
Published: June 2009

The hydrolytic, reductive and oxidative enzyme systems involved in the phase I biotrans formation of xenobiotic compounds have been investigated inHymenolepis diminuta. AdultH. diminutaare able to carry out a range of hydrolytic and reductive reactions, but in common with other helminths oxidative detoxification reactions were absent (oxidative demethylation, aniline hydroxylation, nitrobenzene hydroxylation, biphenyl hydroxylation). These oxidative reactions were readily demonstrated in rat liver. Extracts ofH. diminutahydrolysed nitrophenylphosphates and inorganic pyrophosphate, but not arylsulphates, nor could epoxide hydratase activity be detected.N-Deacetylaseactivity was present. However,O-deacetylase activity could not be demonstrated, although butyrate and palmitate, but not benzoate, esters were hydrolysed.H. diminutawas capable of hydrolysing a range of a-and β-glycosides, but not β-glucuronides. Extracts ofH. diminutareduced azo-compounds, aldehydes and disulphides, but ketones and aromatic nitro-compounds were not reduced. The phase I detoxification systems ofH. diminutadiffer considerably from those of its rat host; the results also suggest that, within the cestodes, there may be considerable species variation in detoxification reactions.
The effect of host density on the establishment and fecundity of Heligmosomoides polygyrus
Authors: Kerboeuf Dominique
Published: June 2009

The effect of mouse population density on the establishment, survival and fecundity of single cohorts of Heligmosomoides polygyrus was investigated. No significant relationship was found between host population density and the worm burden at post mortem. But, lower host population densities were associated with higher parasite fecundities and with higher overall mean daily faecal output. The results might be explained by a decrease in male hormone secretion or digestive disturbances associated with lower ingesta in the higher host population densities. Effects resulting from changes in immunological responses might also exist.
The formation of surface membrane vesicles from schistosomula ofSchistosoma mansoni
Authors: Kusel J. R. , Gazzinelli G. , Colley D. G. , De Souza C. P. S. , Cordeiro M. N.
Published: June 2009

Intact surface membrane vesicles were obtained and purified from the schistosomula ofSchistosoma mansoni. The method of preparation of the vesicles involved treating the schistosomula in a buffered high salt medium for 1 h at 4°C (Step 1), and then for 1 h at 25–37°C (Step 2). Vesicles were formed from mechanically- and skin-transformed schistosomula, and their size and number depended on the temperature of Step 2. The majority of the vesicles expressed surface membrane concanavalin A receptors and parasite antigens on their outermost surfaces. When incubated with sensitized peripheral blood mononuclear cell preparations from humans exposed to schistosomal preparations, the vesicles stimulated lymphocyte transformation as effectively as soluble egg and adult worm antigens. Although both preparations contained identical proteins, small vesicles were less effective than large vesicles in stimulating lymphocyte transformation. Hence, vesicles prepared under a variety of conditions might be used to study those factors which influence the presentation of membrane-bound surface antigens to the immune system of the host.
Helminths and the transmammary route of infection
Authors: Miller Grover C.
Published: June 2009

The transfer of infective larval stages of helminths via the mammary glands is probably more common than generally recognized. Recent investigations of both natural and experimental infections of various animals have shown that the transmammary transmission of some helminths is a major avenue of infection. Other studies indicate that there are at least 13 helminth parasites which may be transmitted as prenatal infections and at least 17 transmitted via the mammary glands. The majority of these are nematodes. However, in one case the tetrathyridia of the cestode Mesocestoides was observed. In this report the life-cycle and transmission of 2 species of diplostomatid trematodes in the genus Pharyngostomoides is described. The raccoon, Procyon lotor, is the only definitive host; a planorbid snail, Menetus dilatatus, and a branchiobdellid annelid, Cambarincola osceola, a commensal on crayfishes, are intermediate hosts. Records for a period of 11 years are now available for the maternal transmission and longevity of this trematode. During this time one infected female raccoon was maintained in the laboratory on a diet of commercial dog food, sweet potatoes and corn. She produced 25 offspring, most of which were infected with Pharyngostomoides, through the 6th litter. There was a declining number of worms in each litter, ranging from nearly 2000 in one of the 1st litter, to none in the 7th litter. After nearly 12 years she continues to pass a few trematode ova. Rather than assume she has retained the same adult worms for 12 years, it is reasonable to conclude that mesocercariae move through her body and eventually mature in the intestine. Because the mesocercariae have a predilection for the lactating mammary gland, it seems likely that a hormonal influence is present. The transmammary transmission of larvae is a viable alternative in the life-cycles of a number of helminths, and in some instances it is probably the major route of infection.
Functional antigens of Trichuris muris released during in vitro maintenance: their immunogenicity and partial purification
Authors: Jenkins S. N. , Wakelin D.
Published: June 2009

The immunogenicity of the secretory exo-antigen (EXA) originating in the stichosome of Trichuris muris has been investigated. High levels of immunity to challenge were produced using EXA (100 μg) by subcutaneous administration. Vaccination with a range of doses of EXA in Freunds' Incomplete Adjuvant (FIA) showed a dose response; 1 μg of EXA reduced the worm burden by 50% and doses of 10 μg or more reduced the worm burden by 80–90% at Day 9 post-infection. Worms recovered from vaccinated mice were significantly smaller than those from controls. A precipitin line identifiable with EXA was shown to immunize mice against T. muris challenge by vaccination. The protective antigen contained in EXA has been partially isolated using gel filtration, ion exchange filtration and isoelectric focusing and has been shown to be a protein of 30000 molecular weight having a pi of 6·8–7·3.
Immunity to an attenuated variant ofPlasmodium berghei: role of some non-specific factors
Authors: waki Seiji , Nakazawa Shushke , Taverne Janice , Targett G. A. T. , Playfair J. H. L.
Published: June 2009

Plasmodium bergheiXAT, an attenuated variant of lethalP. berghei, causes a resolving infection in Balb/c mice from which they recover in about 3 weeks. The parasitaemia displays an early peak at about 5 days, followed by a steep drop in parasite number associated with the appearance of degenerating forms inside mature erythrocytes; the parasites remaining are inside reticulocytes. By contrast, no degenerating parasites were seen in infections caused by the virulent parent, which was mainly confined to mature erythrocytes. However,P. bergheiXAT was no more sensitive to reactive O2metabolites, generated by alloxan, or to tumour necrosis serum, than its virulent parent. Furthermore, its early drop in parasitaemia was unaffected by silica. The drop still occurred in the absence of T cells, although the infection was then ultimately lethal, and it was not mediated by NK cells since it occurred in nude mice treated with anti-asialo GM1 serum to abolish NK cell activity. However, it was absent in splenectomized mice, in whichP. bergheiXAT infection was lethal. Thus, the attenuation ofP. bergheiXAT infection is not due to increased susceptibility to some of the agents thought to cause parasite destruction, but to some other mechanism in which the spleen is involved.
Use of species-specific DNA probes for detection and identification of trypanosome infection in tsetse flies
Authors: Kukla B. A. , Majiwa P. A. O. , Young J. R. , Moloo S. K. , ole-Moiyoi O.
Published: June 2009

Species- and subspecies-specific trypanosome DNA hybridization probes have been employed in the detection and identification of trypanosome infections inGlossina morsitans centralis.Several ways of sample preparation including the use of tsetse organ suspensions, proboscides and dissected midguts, as well as tsetse abdominal content touch-blots were explored. The results of hybridization of radio-isotope-labelled species-specific DNA probes to tsetse samples indicated that it was possible to detect trypanosomes in the organs where parasite development is known to characteristically occur for each subgenus. Duplicate slot-blots of samples prepared from midguts of tsetse infected with 2 strains ofT. congolenseand from non-infected fly controls show that it is not only possible to detect infection in tsetse but also to identify the strain of parasite present in a sample after hybridization with the DNA probes specific for each strain. The results, obtained after hybridization of sequential abdominal touch-blots from the same fly with the DNA probe specific for one strain ofT. congolense,indicated that at least 8 positive signals can be observed after an overnight exposure. Because of their simplicity and potentially low cost, the techniques described here would be appealing for screening large numbers of tsetse samples from the field for the presence of any trypanosome residing in the guts or proboscis of the vector. In addition, the possibility of doing multiple touch-blots from the same fly gives the opportunity of detecting mixed trypanosome infections in the vector.
Regulation of mouse colony abundance byHeligmosomoides polygyrus
Authors: Scott Marilyn E.
Published: June 2009

Despite the ubiquitous presence of parasites, parasitism has not been considered among the list of regulatory factors in animal populations until recently. A detailed long-term study on the impact of the direct life-cycle nematodeHeligmosomoides polygyruson a breeding population of laboratory mice provides a clear example of the ability of helminths to regulate host abundance. In the absence of the parasite, the mouse population equilibrated at a density of 320 mice/m2as a result of density-dependent effects on recruitment. When the parasite was added and transmission was maintained at high levels, infected mouse populations equilibrated at densities of < 18 mice/m2. Reduced rates of parasite transmission and elimination of the parasite from the system both resulted in an increase in mouse density. These results have implications for both ecology and parasitology as they demonstrate a potentially important but often ignored component of host populations that may well influence host abundance and community structure.
Implantation of adult Onchocerca gutturosa into laboratory rodents
Authors: Sinnary K. A. El , Bianco A. E. , Williams J. F.
Published: June 2009

Adult males and females ofOnchocerca gutturosawere implanted into the peritoneal cavity of mice, and their survival was determined at intervals thereafter by post-mortem examination. Ten of 17 animals receiving males dissected free of bovine host tissues contained live parasites at necropsy up to 4 months later. Female worms digested free from connective tissue by collagenase did not survive well, even though they appeared motile and intact before implantation; only 2 were alive 10 days later in 2 of 16 recipients. When males and females still contained within connective tissue capsules were implanted they survived for up to 2 months, and microfilariae were detected transiently in the skin of 2 recipient mice. The results suggest the feasibility of maintaining adultO. gutturosain rodents by this means, provided exposure of worms to enzymes used to free them from host tissue is avoided.
Biology of gyrocotylideans with emphasis on reproduction, population ecology and phylogeny
Authors: Williams H. H. , Colin Judith A. , Halvorsen O.
Published: June 2009

The Gyrocotylidea is a group of platyhelminths comprising only a dozen or so species which have been placed in three genera,OyrocotyleDiesing, 1850,AmphiptychesGrube and Wagener in Wagener, 1852 and Gyrocotyloides Fuhrmann, 1930. All species are highly specific to chimaeroid fish, a small group of present-day holocephalans, and are restricted to the spiral valve intestine of these hosts.
Babesia vesperuginis:natural and experimental infections in British bats (Microchiroptera)
Authors: Gardner R. A. , Molyneux D. H.
Published: June 2009

Babesia vesperuginisis described from blood of two species of British bat:Pipistrellus pipistrellusandMyotis myslacinus. Reticulocytes appeared significantly elevated in blood films ofP. pipistrellusinfected withB. vesperuginiscompared with uninfected laboratory-maintained bats or apparently uninfected wild-caught bats. Infected captive bats had significantly enlarged spleens.B. vesperuginiswas transmitted by inoculation of infected blood to 5 uninfected captiveP. pipistrellus. The course of infection followed a pattern of a rising parasitaemia accompanied by a rise in reticulocytes, followed by a fall in parasitaemia to low (<0·1%) or undetectable levels. When sacrificed, theBabesia-infected bats had significantly lowered blood haemoglobin, significantly raised white blood cell counts and enlarged spleens compared to uninfected bats. Attempts to transmit the parasite to irradiated and athymic ‘nude’ mice by inoculation of infected blood were unsuccessful. The experimental results and observations of infected wild bats indicate the potential pathogenicity ofB. vesperuginisto bats. It is likely that the vector ofB. vesperuginisisArgas vespertilionisbecause no Ixodid ticks were found onP. pistrellus.
The response toSchistosoma bovisin normal and T-cell deprived mice
Authors: Murare H. M. , Agnew Alison , Baltz Marilyn , Lucas S. B. , Doenhoff M. J.
Published: June 2009

Normal and T-cell deprived mice have been compared in their response to infection withSchistosoma bovis. The deprived mice survived longer than comparably infected, immunologically intact controls, despite an increased longevity of the adultS. bovisworms in the former animals giving rise to higher tissue egg densities. The reduced pathology in deprived mice was due to inhibition of T-cell dependent granuloma formation around tissue-bound schistosome eggs, with concomitantly decreased tissue disruption as evidenced by smaller spleens and lower circulating transaminase concentrations. These observations onS. boviscontrast with the greater morbidity and earlier mortality induced byS. mansoniin T-cell deprived mice, the latter due to an hepatotoxic potential ofS. mansonieggs that is expressed in the absence of the host immune response. The absence of hepatocyte damage aroundS. boviseggs in deprived mice indicates that this schistosome lacks such a toxin, and this could explain why duringS. bovisinfection synthesis of the two acute-phase proteins, complement C3 and serum amyloid P-component (SAP) here seemed less T-dependent than has previously been found duringS. mansoniinfection of mice. In a time-course experiment the hypergammaglobulinaemia induced byS. bovis, and the specific IgG antibody response against egg antigens were significantly T-cell dependent during the early stages of patency. Similarly, in most experiments assayed once between 9 and 11 weeks afterS. bovisinfection, deprived mice had significantly reduced hypergammaglobulinaemias, and reduced specific IgM and IgG antibody responses against both worm and egg antigens.
Effects of a series of infections ofOstertagia circumcinctaon gastric secretion of sheep
Authors: Anderson N. , Blake R. , Titchen D. A.
Published: June 2009

Sheep which had been either previously infected withO. circumcinctaor maintained worm-free, were surgically prepared with separated fundic pouches and abomasal cannulae and subsequently infected with 20000O. circumcinctalarvae three times weekly.

A reduction in food intake and increases in total acid output from the pouches and plasma pepsinogen levels were evident in both groups of sheep 4 days after repeated infections commenced; effects which increased in severity after 12 or more days. Except for a transient period of slight failure, previously infected sheep retained the capacity to acidify their abomasal contents whereas previously worm-free sheep lost this capacity. These changes were reversed between 2 and 7 days after treatment with thiabendazole (88 mg.kg−1).

Secretory capacity of the fundic pouches was tested with histamine (40 μg.kg−1), the histamine antagonist (burimamide 8mg.kg−1) and atropine (100 μg kg−1). Ostertagiasis reduced or abolished the stimulatory effects of histamine. An increase in secretion volume and acid output was obtained after food was freshly provided, even though as little as 25 gm was consumed. Atropine and burimamide both caused a profound decrease in pouch secretion and acid output.

These data are consistent with the hypothesis previously stated that in ostertagiasis the hypersecretion from fundic pouches is due to increased levels of circulating gastrin.
Qualitative and quantitative histochemical changes in the caecum and liver of turkeys infected withHistomonas meleagridis
Authors: Wilkins D. , Lee D. L.
Published: June 2009

Changes in the amount and distribution of acid and alkaline phosphatase, non-specific esterase, glycogen, lipid and acid mucopolysaccharide in the caecal wall and liver of turkey poults infected withHistomonas meleagridishave been studied histochemically. A microdensitometer was used to measure changes in activity and distribution of acid phosphatase and non-specific esterase in the caecal mucosa. During the course of the infection there is a marked reduction in activity and distribution of acid phosphatase and non-specific esterase but little change in the amounts and distribution of alkaline phosphatase, glycogen, lipid and acid mucopolysaccharide in the wall of the main part of the caecum. Similar, but smaller, changes occurred in the wall of the neck region of the caecum. In the liver most changes occurred in the immediate vicinity of the parasites. Initially, there was a reduction in the amount of glycogen in the parasitic lesions but later in the infection there was a marked loss of glycogen in all regions of the liver. Changes in the caecum are apparently brought about by the parasite prior to and after invasion of the caecal tissues; changes in the liver occur after it has been invaded.
The feeding behaviour of larvae, nymphs and adults of Rhipicephalus appendiculatus
Authors: Tukahirwa E. M.
Published: June 2009

The pre-feeding and feeding periods of larvae, nymphs and adults of Rhipicephalus appendiculatus on rabbits (Oryctolagus cuniculus) were investigated. Larvae and nymphs required at least 8–9 days after hatching and moulting respectively before they could attach and start feeding, while adults required at least 6–9 days. But longer periods of starvation improved the proportion of ticks that successfully fed.

After attachment, there was always an initial period of slow feeding, which was followed by a phase of very rapid feeding before the engorged ticks detached from the host. Larvae detached 4–5 days after attachment, nymphs detached after 5–6 days and adults detached 7–9 days after attachment.
The tegument ofSchistosoma mansoni: a histochemical investigation
Authors: Wheater P. R. , Wilson R. A.
Published: June 2009

The main components of the schistosome tegument were found to be neutral glycoprotein and phospholipid; a small quantity of glycolipid was observed in the male dorsal tegument. The tegument can be differentiated from other schistosome tissues on the basis of enzyme content; three hydrolytic enzymes were shown to be specifically localized in the tegument: alkaline phosphatase, adenosine triphosphatase and indoxyl esterase. It is suggested that these enzymes could be used as intrinsic markers for tegument structures. The subtegumental cells appear to be the major sites of biosynthetic activity since they contain large amounts of RNA and mitochondrial enzymes.
Superoxide dismutase fromAscaris suum
Authors: Sanchez-Moreno M. , Monteoliva M. , Fatou A. , García-Ruiz M. A.
Published: June 2009

Three superoxide dismutases (SOD) (EC 1.15.1.1) were detected in homogenates ofAscaris suum. Each of the three forms of SOD was purified by a sequence of multiple differential centrifugations, ammonium sulphate precipitation, ion-exchange chromatography and G-75 Sephadex column chromatography. The three forms of SOD were present in different cellular locations; one in the cytoplasmic fraction, sensitive to cyanide and hydrogen peroxide, and two in the mitochondrial fraction, one of which was cyanide sensitive. The SOD forms presented clear differences in their electrophoretic patterns. The sexual organs of females showed the highest SOD activities of all the tissues examined. The finding of such high levels of superoxide dismutase inA. suumreflects the importance of this enzyme in the metabolism of this helminth parasite.
Characterization of coccidial proteins by two-dimensional sodium dodecyl sulphate–polyacrylamide gel electrophoresis
Authors: Sutton C. A. , Shirley M. W. , Wisher M. H.
Published: June 2009

Two dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (2D SDS–PAGE) has been used to produce ‘fingerprint’ maps of the proteins from each of the 7 species ofEimeriawhich infect the chicken. All 7 species could be identified from their array of polypeptides but few differences were detected between strains of the same species. Alterations to the polypeptide array associated with the stage of sporulation of the oocysts were observed. lodination of sporozoites, 2D SDS–PAGE, autoradiography and immunoblotting techniques were combined to identify polypeptides with a surface moiety and those which were antigenic.
Origin, kinetics of circulation and fatein vivoof the major excretory–secretory product ofAcanthocheilonema viteae
Authors: Harnett W. , Worms M. J. , Kapil A. , Grainger M. , Parkhouse R. M. E.
Published: June 2009

The excretions-secretions (E-S) ofAcanthocheilonema viteaeconsist mainly of one product, molecular weight 62 kDa. This molecule is synthesized during the vertebrate phase of the parasite life-cycle and is first detectable in the E-S of L4 parasites. It is cross-reactive with E-S of human filarial parasites as a consequence of possessing a phosphorylcholine (PC) moiety. The 62 kDa molecule has been employed as a model for the study of the origin and fate of filarial E-S. Immunohistological analysis has shown the molecule to be located predominantly in the parasite gut. Transplantation of adult female [S] methionine pulsed worms into uninfected jirds resulted in the radio-labelled secreted 62 kDa antigen being detected in the bloodstream within 4 h by SDS–PAGE/immunoprecipitation analysis. The systemic half-life of the molecule as estimated by clearance of injected, purified I-labelled material was measured in naive and infected jird hosts.
The role of parasite fecundity and longevity in the success of Trichostrongylus tenuis in low density red grouse populations
Authors: Shaw J. L. , Moss R.
Published: June 2009

The prevalence of the caecal threadworm Trichostrongylus tenuis in red grouse in the north of Scotland was high despite low grouse densities. Prevalence, intensity and aggregation of threadworms was higher in old than in young grouse. Infections were long-lasting: populations of adult worms could survive for over 2 years in grouse, with little mortality. Parasite egg output decreased with the age of a worm population, largely as a result of a decrease in the fecundity of ageing female worms. Seasonal variations in worm fecundity were also evident.However, there was no evidence of an intensitydependent decrease of worm fecundity with increasing worm numbers in either captive or wild grouse. The long life and high reproductive capacity of T. tenuis probably contribute to its effective transmission and high prevalence.
A hybrid gene to express protein epitopes from both sporozoite and merozoite surface antigens of Plasmodium falciparum
Authors: Holder A. A. , Lockyer M. J. , Hardy G. W.
Published: June 2009

The DNA coding for parts of the repetitive amino acid sequence of the Plasmodium falciparum circumsporozoite protein has been spliced to a sequence encoding part of the precursor to the major merozoite surface antigens, to produce a hybrid gene. Expression in Escherichia coli produces a protein with antigenic determinants from both malaria proteins. Antibodies raised against the expressed material react with both a peptide derived from the circumsporozoite repeat sequence, and the merozoite surface molecule. Hybrid molecules of this type may be the basis of a malaria vaccine.
Excreted/secreted products of developing Taenia saginata metacestodes
Authors: Joshua G. W. P. , Harrison L. J. S. , Sewell M. M. H.
Published: June 2009

Excretions and secretions (ES) and somatic components of 4, 8, 12 and 16-week-old Taenia saginata metacestodes were biosynthetically radio-isotope labelled by incubating the larvae in the presence of [35S]methionine. Despite their small size, 4-week-old metacestodes produced as much isotope-labelled ES/parasite as older metacestodes, indicating a proportionately greater metabolic activity of the parasite at this age. In situ the 4-week-old metacestodes were surrounded by a marked granulomatous cellular infiltrate which had largely resolved around 8-week-old metacestodes. Examination of the isotope-labelled ES by SDS-PAGE revealed distinct age-specific components from 4- and 12-week-old metacestodes and other ES components which were produced by all the ages of metacestodes examined. In comparison the labelled somatic components were conserved. Antigenic characterization of the ES by immunoprecipitation against a panel of clinically defined bovine sera combined with SDS-PAGE analysis, identified some highly immunogenic parasite products and others which did not elicit an antibody response demonstrable by immunoprecipitation. These components are of interest in relation to the host/parasite relationship, to the construction of diagnostic assays for the detection of T. saginata cysticercosis, and to the immunity that cattle develop against this parasite.
Schistosoma mansoni: evidence that ‘non-permissiveness’ in 129/Ola mice involves worm relocation and attrition in the lungs
Authors: Elsaghier A. A. F. , Knopf P. M. , Mitchell G. F. , Mclaren D. J.
Published: June 2009

129/Ola mice resemble WEHI 129J mice in that around 70% of the individuals in any given population resist a primary infection withSchistosoma mansoni. Squashed-organ autoradiographic tracking of [Se]selenomethionine-labelled parasites has shown that the kinetics of worm migration in 129/Ola mice follows the expected pattern, and that all rodents harbour essentially similar numbers of worms on day 14 post-infection. Combined lung and liver worm recovery techniques have revealed, however, that segregation of mice into ‘permissive’ and ‘non-permissive’ individuals can first be detected on day 20. ‘Non-permissive’ mice are characterized by the absence of schistosome eggs at all times in the liver parenchyma and, in consequence, lack the attendant manifestations of pathology; they do, however, harbour a few stunted worms in the liver and significant numbers of adult schistosomes in the pulmonary vasculature. Histological analysis of sectioned lung tissue from such animals indicates that some lung-located schistosomes feed, pair and lay eggs. Nevertheless, eosinophil-enriched inflammatory reactions develop around such worms and the parasites themselves exhibit various manifestations of trauma, ranging from minor vacuolation to gut herniation and extrusion. The phenomenon of ‘non-permissiveness’ thus involves retardation of worm development in the liver and, in consequence, relocation of the parasites to the lungs, where they become subject to host effector responses.
Portal shunting and resistance to Schistosoma mansoni in 129 strain mice
Authors: Coulson P. S. , Wilson R. A.
Published: June 2009

The integrity of the hepatic portal vasculature was examined, relative to the resistance to Schistosoma mansoni observed in 68°0 of 129/Ola mice. The passage of microspheres to the lungs, following their injection via the superior mesenteric vein, indicated the presence of shunts in the majority of both naive and infected mice. There was a negative association between shunting of microspheres to the lungs and paucity of liver worms at 28/35 days post-infection. Schistosomula accumulated in the livers of resistant mice at a slower rate than in susceptible animals, and after day 21 relocated to the lungs. Many lung schistosomula injected via the superior mesenteric passed immediately to the lungs; the shunts thus greatly reduce the probability of trapping in the liver. Some parasites migrated back from the lungs, successfully lodged in the liver and began to feed on blood. Latex infusion demonstrated the location of large intrahepatic connections between the portal and hepatic veins. We suggest that as these liver worms grow, migrating upstream into progressively larger vessels, they reach the connections, pass out of the hepatic portal system, and relocate to the lungs. The presence of the natural shunts thus accounts for the resistant status of the mice.
Analysis of a genetic cross between Trypanosoma brucei rhodesiense and T. b. brucei
Authors: Gibson W. C.
Published: June 2009

Two trypanosome clones, representing East and West African homozygotes at 2 isoenzyme loci (T. b. rhodesiense MHOM/ZM/74/58 [CLONE B] and T. b. brucei MSUS/CI/78/TSW 196 [CLONE A]), were cotransmitted through tsetse flies and the resulting trypanosome populations checked for the presence of non-parental karyotypes by pulsed-field gel electrophoresis. Ten clones isolated from these populations proved to have 5 different recombinant genotypes by analysis of nuclear and kinetoplast DNA (kDNA) polymorphisms. It is inferred that genetic exchange occurred between the 2 trypanosome clones in the fly, as previously reported for 2 other T. brucei spp. clones by Jenni and colleagues. For the most part, the hybrid clones shared many characteristics with both parents and their genotypes were consistent with segregation and reassortment of parental alleles. The least amount of genetic material exchanged was kDNA alone. Regarding the mechanism of genetic exchange, several hybrid clones had identical and unique nuclear DNA polymorphisms, but different kDNA type. Assuming that the same reassortment of nuclear markers is unlikely to occur by chance, these clones most probably arose from a predecessor carrying both types of kDNA.
Modification of cellular immunity byTaenia multiceps(Cestoda): accessory macrophages and CD4+lymphocytes are affected by two different coenurus factors
Authors: Rakha N. K. , Dixon J. B. , Jenkins P. , Carter S. D. , Skerritt G. C. , Marshall-Clarke S.
Published: June 2009

Taenia multicepscoenurus fluid was analysed by fast protein liquid chromatography in order to separate the factors responsible for previously reported modification of immunological activity in macrophages and T-cells. One factor, F7, was found to be mitogenic for murine L3T4+T-cells, to be macrophage dependent, to require macrophage compatibility at the I region of the H2 complex, to increase the sensitivity of T-cells to regulatory signals from macrophages and to increase the rate of generation of splenic rosette-forming cells (RFC) against sheep red cells. A second factor, F24, was found to alter macrophages so as to render them suppressive, rather than stimulatory, for parasite-activated and Con A-activated lymphocyte transformation, to depress the rate of generation of RFC and to antagonize the mitogenic effect of F7. The combined actions of these two factors are, therefore, sufficient to explain the known immunomodulatory effects of the metacestode.
Reduced accumulation of isometamidium by drug-resistant Trypanosoma congolense
Authors: Sutherland I. A. , Peregrine A. S. , Lonsdale-Eccles J. D. , Holmes P. H.
Published: June 2009

The accumulation of the trypanocide isometamidium chloride (Samorin®, RMB Animal Health Ltd, UK) by a range of clones of Trypanosoma congolense with varying sensitivity to the drug, was measured by methods based on the fluorescence of isometamidium. Fluorescence microscopy and flow cytometry showed a reduction in drug accumulation by resistant clones. Fluorescence spectrophotometry demonstrated an inverse correlation between the intensity of cell-associated fluorescence and the level of resistance of the clones expressed in vivo. The addition of the metabolic inhibitor SHAM/glycerol to the incubation medium resulted in a reduction of this apparent difference in drug accumulation between the clones; those clones which were sensitive to isometamidium showed a reduction in fluorescence while a percentage increase in fluorescence was observed as clones became more resistant to the trypanocide. These observations may be of value for the in vitro detection of resistant T. congolense populations and may also be used to estimate the mean level of resistance in a given sample. The results also imply that decreased accumulation of isometamidium by drug-resistant clones of the parasite may be responsible for the reduction in sensitivity.
Spatial and temporal heterogeneity in the population dynamics ofBulinus globosusandBiomphalaria pfeifferiand in the epidemiology of their infection with schistosomes
Authors: Woolhouse M. E. J. , Chandiwana S. K.
Published: June 2009

Populations ofBulinus globosusandBiomphalaria pfeifferiwere studied in a river habitat in Zimbabwe over a period of 12 months. Data were obtained on the prevalences of infections ofSchistosoma haematobium(alsoS. mattheei) andS. mansonirespectively. Population parameters showed the following patterns for both snail species. (1) A patchy distribution correlated with the distributions of aquatic plants. (2) Life-expectancies of only a few weeks. (3) Recruitment rates correlated with water temperature and showing a distinct seasonal peak. (4) Spatial variation in recruitment. (5) A redistribution of snails during the rainy season. Epidemiological parameters showed the following patterns. (1) Large seasonal variations in the prevalence of patent infections. (2) Evidence from size-prevalence curves that suggests a variable force-of-infection from man to snail, correlated with water temperature. (3) Prevalences of infection that were higher in the vicinity of (±60 m from) major water contact sites. Local prevalences of infection forB. globosussometimes exceeded 50% and may have approached 100% if pre-patent infections are included. Snail numbers may limit transmission at these locations. Attention is drawn to the need to make field observations at an appropriate spatial scale and also to the implications for the effectiveness of focal snail control as a means of reducing transmission.
Studies on motilityin vitroof an ectoparasitic monogenean,Diclidophora merlangi
Authors: Maule A. G. , Halton D. W. , Allen J. M. , Fairweather I.
Published: June 2009

An isometric transducer system has been used to record spontaneous motor activity inDiclidophora merlangi in vitro. Motility took the form of either continuous irregular contractions or bursts of activity with intermittent quiescent periods. Maximal activity was recorded from specimens at 5–8 °C in artificial sea water (ASW). Decerebration induced a period of enhanced motility which subsided within 1 h. Water turbulence elicited large, rapid contractions of the longitudinal body musculature which did not habituate or fatigue. Induced water turbulence at frequencies higher than 3/min inhibited spontaneous movements, resulting in a progressive reduction in contraction amplitude and, eventually (30/min), the abolition of any response to water movement. The neurotoxin tetrodotoxin failed to modify worm activity. Excitatory responses from both intact worms and strip preparations were obtained with 5-hydroxytryptamine, dopamine and noradrenaline, but aminergic antagonists failed to block their effects. Atropine stimulated contractility, whereas the effects of acetylcholine or carbachol were inconsistent. Nicotine increased muscle tone but the effect was unaltered by atropine, mecamylamine ord–tubocurarine. Muscarine, hemicholinium, neostigmine and eserine were without apparent effect.
Schistosoma mansoni:analysis of the humoral and cellular basis of resistance in guinea-pigs vaccinated with radiation-attenuated cercariae
Authors: McLaren D. J. , Delgado V. S. , Gordon J. R. , Rogers M. V.
Published: June 2009

This study addresses the humoral and cellular basis of specific acquired immunity in the guinea-pig irradiated vaccine model of schistosomiasis mansoni. Rodents vaccinated with 500 gamma-irradiated cercariae and then splenectomized 4·5 weeks later showed a 33% reduction in resistance to challenge as compared to vaccinated animals or vaccinated/sham splenectomized controls. Serum harvested from once vaccinated individuals conferred modest levels of resistance upon naive recipients in some experiments, but transfer was not achieved consistently. Serum from vaccinated and thrice boosted rodents (Vbbb) routinely transferred around 45% immunity, however, provided it was given in 4 ml aliquots on day 9 post-challenge; Vbbb serum thus transferred 50% of donor immunity. Interestingly, multiple doses of this protective serum given on and either side of day 9 did not enhance the protection achieved with a single 4 ml aliquot. Neither peripheral lymph node cells nor splenocytes from the polyvaccinated serum donors were able to transfer resistance to recipient guinea-pigs and they failed to augment the protection achieved with Vbbb serum. Food-pad testing revealed no correlation between delayed hypersensitivity responses and immunity to challenge in vaccinated guinea-pigs. Although polyvaccine guinea-pig serum successfully protected homologous recipients, it failed to protect mice when administered either at the time of challenge (the optimal schedule for transfer of polyvaccine mouse serum), or around day 9 (the optimal schedule for guinea-pigs). Similarly, guinea-pigs could not be protected with polyvaccine rat serum that conferred 75% resistance upon naive recipient rats.
Evidence that radio-sensitive cells are central to skin-phase protective immunity in CBA/Ca mice vaccinated with radiation-attenuated cercariae ofSchistosoma mansonias well as in naive mice protected with vaccine serum
Authors: Delgado V. S. , McLaren D. J.
Published: June 2009

Naive CBA/Ca mice and CBA/Ca mice vaccinated 4 weeks previously with radiation-attenuated cercariae ofSchistosoma mansoniwere subjected to 550 rad of whole body (gamma) irradiation and then challenged 3 days laterwith normal cercariae. The perfusion recovery data showed that this procedure reduced theprimary worm burden in naive mice by 22% and the challenge worm burden in vaccinated mice by 82%. Irradiation also ablated the peripheral blood leucocytes of both mouse groups by 90%–100% at the time of challenge. Histological data revealed that such treatment caused a dramatic change in number, size and leucocyte composition of cutaneous inflammatory skin reactions that characterize challenged vaccinated mice and are known to entrap invading larvae; cutaneous eosinophils were preferentially abolished by this treatment. Polyvaccine mouse serum that conferred protection passively upon naive recipient mice, failed to protect naive/irradiated mice when administered by the same protocol. Distraction of macrophages by treatment of mice with silica did not affect the establishment of a primary worm burden and reduced the protection exhibited by vaccinated mice by only 16%. These data indicate that radio-sensitive cells are important to both innate and specific acquired resistance in this mouse model and that macrophages contribute only marginally to the expression of vaccine immunity.
Epitopes expressed on very lowMrSchistosoma mansoniadult tegumental antigens conform to a general pattern of life-cycle cross-reactivity
Authors: Simpson A. J. G. , Hagan P. , Hackett F. , Omer Ali P. , Smithers S. R.
Published: June 2009

The relationship between antigens associated with the surface of newly transformed schistosomula ofSchistosoma mansoniand the tegumental surface membrane of adultS. mansoniworms has been further explored. Immunoprecipitation of detergent-solubilized125I-tegumental surface membrane antigens of adultS. mansoniwith antibodies from mice vaccinated with highly irradiatedS. mansonicercariae revealed major antigens of Mr32, 20, 15 and 8K. The Mr32 and 20K antigens have been previously demonstrated to be antigenically and electrophoretically identical to major antigens on the schistosomulum surface. The Mr15 and 8K antigens, on the other hand, have not been identified by the immunoprecipitation of125I-schistosomulum surface antigens, although a distinct schistosomulum surface antigen of Mr15K is precipitated by antibodies from mice vaccinated with highly irradiated cercariae. Nevertheless, it was shown that antibodies to the Mr15 and 8K antigens were specifically absorbed from vaccinated mouse serum by intact, live schistosomula, demonstrating that the Mr15 and 8K antigens are exposed on or released from the schistosomulum surface. In contrast, absorption of the antiserum with eggs failed to remove antibody against any of the four tegumental membrane antigens examined. The Mr15 and 8K antigens were shown to be recognized via polypeptide epitopes and not periodate-sensitive carbohydrate epitopes, further emphasizing the similarity of these to the well-characterized Mr32 and 20K tegumental surface membrane antigens. A general relationship between schistosomulum surface, adult tegumental membrane and egg antigens was demonstrated by ELISA, using antibodies raised against the three antigenic fractions. It was shown that both the egg and adult tegumental membrane antigens cross-react with the schistosomulum surface, but that the egg and adult membrane antigens exhibit very little, if any, mutual cross-reactivity. This antigen divergence possibly enables the host to dissociate pathological, anti-egg responses from potentially protective anti-membrane responses during the course of natural infection. It also suggests that adult membrane antigens could be used in an anti-schistosome vaccine without the possible complication of inducing pathological responses.