bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulsed transmission of Pseudodiplorchis americanus (Monogenea) between desert hosts (Scaphiopus couchii)
Authors: Tinsley R. C. , Jackson Helen C.
Published: June 2009

Transmission of the monogenean Pseudodiplorchis americanus is restricted to the brief period when its host, the desert toad Scaphiopus couchii enters temporary water to breed. This study followed parasite recruitment into one host population in Arizona, USA, during the spawning season (July). Torrential rainfall triggered 3 successive assemblies. Amongst males, which may enter each assembly, the 3 pulses of invasion led to an approximate doubling of mean worm burdens at each exposure, culminating in 100% prevalence and a mean intensity of over 100 larvae/host. Females, which generally enter only one assembly, acquired a mean of about 40 larvae/host. Each exposure is limited to a maximum of 7 h by strictly nocturnal host activity, and the force of infection increased exponentially: around 10% of recruitment occurred in the first 3 h, and more than 30% in the last 1 h. Correlation of recruitment into males with parasite reproductive potential suggests that individual oncomiracidia had a 30% chance of invasion. Although invasion of the desert host relies on an aquatic infective stage, host behaviour ensures that targets are concentrated in space and time, and the parasite's annual reproductive output is synchronized with a period of host vulnerability totalling less than 24 h/year.
Plasmodium falciparumgrowth inhibition by human plateletsin vitro
Authors: Peyron F. , Polack B. , Lamotte D. , Kolodie L. , Ambroise-Thomas P.
Published: June 2009

Platelets take an active part in immunological processes as well as in haemostasis, especially in the host-parasite relationship. Our aim is to assess the growth ofPlasmodium falciparum, cultured in human erythrocytes in the presence of fresh washed human platelets, since thrombocytopaenia is frequently observed during malarial infections. Our results show that platelets induce a dose-related growth inhibition ofP. falciparum. Both proliferation and maturation of intraerythrocytic stages of the parasite are inhibited. This growth inhibition is triggered by the parasite itself as neither specific antibodies nor any other components are needed to activate platelets. Activated platelets are directly toxic since complement is not involved. Furthermore, inhibition is not mediated by erythrocyte lysis or by toxic oxygen metabolites. Platelets induce an inhibition ofP.falciparumgrowth, at leastin vitro, although the importance of their role playedin vivoin malarial immunity has yet to be evaluated.
Analysis of surface carbohydrates of Trichobilharzia ocellata miracidia and sporocysts using lectin binding techniques
Authors: Gerhardus M. J. T. , Baggen J. M. C. , Van Der Knaap W. P. W. , Sminia T.
Published: June 2009

Miracidia and in vitro-derived primary sporocysts of the avian schistosome Trichobilharzia ocellata were studied for the expression and the characteristics of glycoconjugate moieties comprising the surface coat. Using a panel of 9 peroxidase labelled lectins, several different lectin binding sites were demonstrated on the larvae. Fixed miracidia have binding sites for 7 of the lectins; wheat-germ agglutinin binds to both the ciliated plates and the tegumental ridges between them; the other 6 lectins bind to the plates only. Three of the miracidia-binding lectins, wheat-germ agglutinin, concanavalin A and peanut agglutinin, also bind to fixed sporocysts. Since the miracidial ridges are devoid of binding sites for concanavalin A and peanut agglutinin, whereas the sporocyst tegument binds these lectins, it appears that these sites become exposed during or shortly after transformation. In saturation experiments, low concentrations of peanut agglutinin and concanavalin A are bound more avidly by sporocysts than by miracidia, indicating a higher binding affinity of the former. The two larval forms do not differ in affinity for wheat-germ agglutinin but they have different binding capacities; when offered in high concentrations, more of this lectin is bound by sporocysts than by miracidia. Lectin binding was competitively inhibited by adding the appropriate free saccharides. Live larvae showed the same lectin binding pattern as did fixed specimens. Proteinase treatment reduced lectin binding to living and, to a lesser extent, to fixed larvae, suggesting that binding sites are constituents of proteoglycoconjugates. After SDS–PAGE of extracts from miracidia and sporocysts and subsequent Western blotting, some of the lectins failed to bind glycoproteins, others reacted with an array of bands. The patterns differed among the lectins and each lectin gave different patterns for miracidia and sporocysts. The results obtained with these two lectin-binding techniques support the conclusion that stage-specific proteoglycoconjugates occur at the surface of T. ocellata larvae.
The influence of desert temperature cycles on the reproductive biology of Pseudodiplorchis americanus (Monogenea)
Authors: Tocque K. , Tinsley R. C.
Published: June 2009

Pseudodiplorchis americanus has an extremely brief opportunity for transmission, restricted to less than 24 h in the year when the host (Scaphiopus couchii) enters water to breed. This strict annual cycle means that invading worms have 1 year to complete reproductive development. Despite this, a large proportion of the parasite suprapopulation is not prepared for transmission at the time of host breeding. The present study correlates detailed soil temperatures for one field site in S.E. Arizona, spanning 3·5 years, with laboratory data on parasite growth and reproductive development at a series of controlled temperatures. Development is totally inhibited at 16°C. Optimal growth and development occurs at 25°C and is slower at both 20°C and a diurnal cycle fluctuating between 20 and 34°C (mean 27°C) (simulating summer temperatures experienced by host and parasite). The effective period for accumulation of infective stages by P. americanus in any one season varies according to the timing of the summer rains in consecutive years. Between 1985 and 1988, the interval between host breedings varied from 11 to 13 months and the period when temperatures were above 20°C varied from 4 to 5·5 months per year. Since the first month post-infection (p.i.) consists of pre-reproductive development, first-year worms have only 3–4·5 months to produce infective larvae. In the shortest seasons, these worms may not be able to complete reproductive preparation in time for the first opportunity for transmission. In different parts of the geographical distribution of S. couchii, different cycles of temperature, rainfall and host breeding occur; varying temperature regimes represent an important abiotic control of P. americanus reproductive biology and transmission.
Immunological relationships during primary infection withHeligmosomoides polygyrus(Nematospiroides dubius): H-2 linked genes determine worm survival
Authors: Behnke J. M. , Wahid F. N.
Published: June 2009

The course of primary infection was studied in BALB and B10 H-2 congenic mouse strains. The duration of infection, as assessed with regular faecal egg counts and worm burdens, was shorter in mice carrying the H-2s, H-2dor H-2qhaplotypes when compared to mice with H-2b. Strains with H-2kwere intermediate. An experiment was carried out to test the hypothesis proposed by Wassom, Krco & David (1987) predicting that the progeny of I–E+vemouse strains crossed with I–E-vestrains, would show susceptibility rather than resistance to infection. This hypothesis was not substantiated by our data and we conclude that it does not apply to primary infections withHeligmosomoides polygyrus. It is proposed that the gene products of at least two loci within the H-2 (associated with the H-2band H-2khaplotypes) are crucial in determining the response phenotype of mice to primary infection withH. polygyrus. One allele, (associated with the H-2bhaplotype) may be preferentially affected by parasite-mediated immunosuppression.
Characterization and immunolocalization of an oocyst wall antigen ofCryptosporidium parvum(Protozoa: Apicomplexa)
Authors: Bonnin A. , Dubremetz J. F. , Camerlynck P.
Published: June 2009

A monoclonal antibody (OW-IGO) raised against purified excysted oocysts ofCryptosporidium parvumreacted in an immunofluorescence assay with the oocyst wall. The corresponding antigen was localized by immunoelectron microscopy in fibrillous material present in the parasitophorous vacuole of developing macrogametes and in the wall of both single and double layered sporulating oocysts. Gold particles were also detected over electron-lucent vesicles of the macrogametes by immunoelectron microscopy. On Western blotting ofC. parvumoocyst extracts, major bands at 250 and 40 kDa and several minor components were recognized by Mab OW-IGO. Almost complete abolition of Western blot reactivity occurred after periodate oxidation of oocyst antigen, suggesting that monoclonal antibody OW-IGO reacts with a carbohydrate epitope. Taken together, our results suggest that a fibrillous glycoproteinic material is released in the parasitophorous vacuole from electron-lucent vesicles during gametogenesis, and later condensed in the oocyst wall.
Asexual blood stages of malaria modulate gametocyte infectivity to the mosquito vector – possible implications for control strategies
Authors: Sinden R. E.
Published: June 2009

In the rodent malarial parasitePlasmodium bergheisexual parasites are produced in a single major wave with maximal numbers between day 7 and day 16. Irrespective of their time of appearance during infection these sexual parasites are equally fertilein vitro. In contrast,in vivoinfectivity to the mosquito is maximal at day 3–5 when gametocyte numbers are only 9% of the peak levels seen between days 7 and 16. Up to 96% of natural potential infectivity of gametocytes for the mosquito is therefore suppressed. The suppression is humoral, reversible and correlates with the appearance of an effective host response to the initial rapid increase in asexual parasitaemia. These data are consistent with published evidence which indicates that a reduction in parasitaemia may cause an increase in infectivity of gametocytes to the mosquito vector. Therefore the impact of strategies aiming to control asexual parasites is re-examined. Inefficient strategies might be predicted to increase and not suppress malaria transmission.
Schistosoma mansoni: larval damage and role of effector cell(s) in the synergy between vaccine immunity and Praziquantel treatment
Authors: Piper K. P. , Mott R. F. , Hockley D. J. , McLaren D. J.
Published: June 2009

A number of authors have demonstrated that the schistosomicidal compound, Praziquantel (Pzq), depends for its action upon the immune status of the host (Sabahet al.1985; Brindley & Sher, 1987; Doenhoffet al.1987). We have attempted to define the synergistic interaction between immuno- and chemotherapy further, using the murine irradiated vaccine model of schistosomiasis mansoni. In vaccinated mice, resistance operates in the skin but not the lungs; drug targeted towards lung-stage worms exacerbates lung-phase immunity, however, as depicted by the increased number and size of inflammatory reactions in the pulmonary tissues. Parasites are often found trapped within such foci. In the present investigation, light and ultrastructural studies have been utilized to examine the nature and extent of damage inflicted upon lung-stage larvae recovered from day 6 Pzq-treated vaccinated mice. Such studies have revealed that damage involves muscle disorganization, internal disruption and occasionally, loss of the tegument; in the latter case, cells are often seen attached to the denuded lung worms. To identify the crucial cellular effector cell(s) involved in the synergy between immuno- and chemotherapy, cell depletion studies have been performedin vivo. It would appear from these experiments that eosinophils or lymphocytes rather than neutrophils or macrophages are important effector cells in this synergy. Histological studies argue in favour of eosinophils being the key effector cells.
Biochemical characteristics of the metacyclic forms ofLeishmania majorandL. mexicana mexicana
Authors: Mallinson D. J. , Coombs G. H.
Published: June 2009

Metacyclic forms ofLeishmania majorand putative metacyclics ofL. mexicana mexicanawere found to occur in abundance in stationary phase cultures. These forms have been compared in several ways with promastigotes from mid-log phase cultures and, in the case ofL. m. mexicana, amastigotes. Metacyclics are smaller, contain less protein and appear more active than other promastigotes. Both forms of promastigote respire at a high rate in the absence of exogenous substrate. The free amino-acid contents of the various forms of the two species have been analysed. They differ in detail but alanine was the major amino acid in all cases. The isoenzyme content of the different forms differed significantly. That of the putative metacyclics ofL. m. mexicanawas in several respects more similar to amastigotes than promastigotes, suggesting that the form is pre-adapted for life in a mammal. Metacyclics ofL. majorapparently did not divide in culture but transformed back over a period of 48 h to mid-log phase cells. The results provide further detail of the molecular differences between mid-log phase and metacyclic promastigotes and confirm that metacyclics are a distinct form in the life-cycle.
Schistosoma mansoni: circulating and pulmonary leucocyte responses related to the induction of protective immunity in mice by irradiated parasites
Authors: Menson Essie N. , Coulson Patricia S. , Wilson R. A.
Published: June 2009

The leucocyte responses in peripheral blood and pulmonary airways are described following vaccination of mice with radiation-attenuated parasites, and subsequent challenge with normal parasites. Percutaneous vaccination stimulated a large and sustained expansion of the circulating lymphocyte pool, more marked than after intradermal vaccination with lung schistosomula which induced comparable levels of resistance. Macrophages and lymphocytes infiltrated the pulmonary airways in response to vaccination by both routes, the lymphocytes being particularly abundant after intradermal vaccination. Exposure of mice to an equivalent number of normal cercariae induced an earlier lymphocytosis of short duration; far fewer macrophages and lymphocytes infiltrated the lungs than after vaccination. An intense but transient pulmonary eosinophilia peaked at 3 weeks after primary exposure to either normal or attenuated parasites. Percutaneous challenge of vaccinated mice elicited higher levels of circulating lymphocytes than challenge of unsensitized controls. However, whilst leucocyte numbers of all cell types were still elevated in the airways at challenge as a consequence of vaccination, no further cellular recruitment was observed coincident with parasite elimination. Our data are compatible with the hypothesis that the mechanism of immunity in once-vaccinated mice involves a T lymphocyte-macrophage interaction triggered by antigen release from lung schistosomula.
Spatial and temporal variation in the infracommunity structure of helminths of Apodemus sylvaticus(Rodentia: Muridae)
Authors: Montgomery S. S. J. , Montgomery W. I.
Published: June 2009

Mean species richness and diversity of the helminth infracommunity of Apodemus sylvaticus in woodland areas of Co. Down, Northern Ireland, varied in time and space. Variation in infracommunity structure among individual hosts, however, always accounted for more than 60% of the variation in the data from different places or different times. Helminth species richness increased with increasing population density, the percentage of the host population 16 weeks old or older, and the proportion of the host population with animal material in their stomachs, at two sites monitored over 33 months. The basis for spatial variation in infracommunity structure is less certain but host dynamics and differences in diet are likely to play some role. It is concluded that analysis at the infracommunity level focuses closely on the potential for species interactions and overlap in resource utilization. Infracommunity structure, at least in the case of A. sylvaticus, varies markedly in time and space and between individual hosts. Such variation should not be ignored in comparative studies.
The effect ofBlastocrithidia triatomae(Trypanosomatidae) on the midgut of the reduviid bugTriatoma infestans
Authors: Jensen C. , Schaub G. A. , Molyneux D. H.
Published: June 2009

The pathogenic flagellateBlastocrithidia triatomaedisrupts the digestion ofTriatoma infestans; the midgut ultrastructure of bugs infected with the flagellate and of uninfected bugs is compared. Third or fourth instar larvae were dissected either unfed or 1 week after feeding.In all uninfected bugs extracellular membrane layers (e.m.l.) covered the apical microvillar border of the epithelial cells. Some midgut regions of bugs infected withB. triatomaeappeared normal but often adjacent cells showed pathological effects. In affected cells the e.m.l. and the microvilli and finally the cells themselves were reduced or destroyed. Correlated with these observations of pathogenicity the method of attachment of parasites changed. When the e.m.l. were present only rarely were flagella found, but on extracellular membrane-free cellsB. triatomaeattached by flagellar enlargement to the microvillar border or, if this was reduced, to the apical host cell membrane. No hemidesmosome-like plaques were found at the attachment site. Although some flagella were inserted into the apical region of the cells no intracellular flagellates were observed.
Schistosoma mansoni:evidence that site-dependent host responses determine when and where vaccine immunity is expressed in different rodent species
Authors: Delgado V. S. , McLaren D. J.
Published: June 2009

Laboratory rodents vaccinated with highly irradiated cercariae ofSchistosoma mansonidevelop significant levels of specific acquired resistance yet effect challenge elimination in different organs. Mice and guinea-pigs are at opposite ends of the spectrum in this respect since, in our hands, vaccinated mice kill challenge parasites in the skin whereas vaccinated guinea-pigs kill challenge parasites predominantly in the liver. To determine whether this phenomenon is host-dependent (site) or parasite-dependent (stage), we have transferred worms harvested from mice or guinea-pigs into vaccinated recipient guinea-pigs. The results show that mouse-derived 5-day lung worms and 9-day liver worms that are essentially refractory to vaccine resistance in mice are indeed susceptible to vaccine resistance in guinea-pigs. Identical levels of susceptibility were recorded for lung-stage larvae introduced via the foot vein so as to experience lung and liver mechanisms, or via the mesenteric vein to bypass the lung, thereby confirming that vaccine resistance in guinea-pigs operates in the liver. Mouse worms and guinea-pig worms exhibited equivalent levels of susceptibility at all stages of development. Thirteen-day-old larvae from either donor species were on the border-line of vulnerability, while 20-day-old worms were totally refractory to vaccine immunity in guinea-pigs. These data show that vaccine immunity in different rodent species is a site-dependent, rather than a stage-dependent phenomenon. There is, however, an upper age limit of schistosome vulnerability which is common to worms harvested from different donor species.
Characterization of major surface and excretory-secretory immunogens ofTrypanosoma cruzitrypomastigotes and identification of potential protective antigen
Authors: Ouaissi M. A. , Taibi A. , Cornette J. , Velge P. , Marty B. , Loyens M. , Esteva M. , Rizvi F. S. , Capron A.
Published: June 2009

The surface antigens ofTrypanosoma cruzitrypomastigotes were identified by immunoprecipitation and were compared with metabolically labelled excretory—secretory products (ES) released by the parasitesin vitro. A series of major immunogenic components in the ES antigens were revealed (160 kDa, 130 kDa and 80–110 kDa). The trypomastigote surface also bears the 130 kDa band and the 80–110 kDa complex. Competition experiments demonstrated the common antigenic structure of the ES and the surface antigens. Two-dimensional analysis of ES antigens immunoprecipitated by human Chagasic serum revealed several spots in the 80–110 kDa region with a wide range of isoelectric points (PI between 5·4 and 6·7). This reflects a charge heterogeneity of these polypeptides. The trypomastigote 85 kDa polypeptide was also identified in the ES antigens by using a monoclonal antibody against this antigen. Two-dimensional analysis of the 85 kDa proteins shed from the surface of trypomastigotes and immunoprecipitated by the monoclonal antibody 155D3 showed 2 major spots: a major part of the 85 kDa polypeptide was found at pH 6·5–6·6, whereas a substantial amount of the antigen was found at pH 5·7. An additional component with molecular weight of approximately 58 kDa and isoelectric points of 6·5 and 6·6, was also visualized. Detection of the 85 kDa polypeptide circulating in serum from patients with acute and chronic Chagas' disease was achieved using an enzyme-linked immunosorbent assay. In addition, the data obtained showed that a polyclonal antibody to the 85 kDa polypeptide could be used to passively induce a partial protection of Fischer rats against acute lethal infection. Thus, the antigens recognized by polyclonal antibody appear to play a role in the development of protective immunity againstT. cruzi.
Blocking factors and the isolation of glutathione transferases from Hymenolepis diminuta (Cestoda: Cyclophyllidea)
Authors: Brophy P. M. , Barrett J.
Published: June 2009

Four acidic glutathione (GSH) transferase forms were isolated from the cytosol of the adult cestode Hymenolepis diminuta by hydroxylapatite chromatography, glutathione-affinity chromatography and chromatofocusing, pH 7–5. The enzymes were dimers of subunit size approximately 24 kDa and accounted for at least 3% of the total soluble protein. The major GSH transferase had limited catalytic activity but may interact with a range of ligands and function as a binding/passive detoxification protein. An endogenous factor interfered with the binding of the crude cytosolic GSH transferase activity to glutathione-dependent affinity matrices but, following partial purification, the GSH transferase activity successfully interacted with the glutathione affinity matrix.
Evidence for widespread occurrence of antibodies toEncephalitozoon cuniculi(Microspora) in man provided by ELISA and other serological tests
Authors: Hollister W. S. , Canning E. U. , Willcox A.
Published: June 2009

The enzyme-linked immunosorbent assay (ELISA) was used to survey human sera for antibodies toEncephalitozoon cuniculiusing spores obtained fromin vitrocultures as antigen. Sera were obtained from patients with tropical diseases, neurological and renal disorders, patients who were HIV positive and those who had been tested for HIV but found to be negative. Sera from inhabitants of the village of Jali, The Gambia and from healthy blood donors were also examined. Numerous sera from all groups except the blood donors gave positive ELISA reactions at dilutions of 1:400. On titration, those with titres of 1:400 were reclassified as negative. Antibody titres of 1:800 and above were considered to be indicative of past or present infections withE. cuniculi. Many of these ELISA seropositives were also positive by IFAT or PAP. When examined by Western blotting of SDS–PAGE protein profiles ofE. cuniculispores, sera from many patients who had a tropical association reacted with the characteristic profiles shown by known positive mouse and rabbit sera. Others in the tropical group showed antibody binding to some but not all of the immunodominant polypeptides and yet others were negative in spite of their reactivity in the ELISA, IFAT or PAP test. Less agreement between ELISA and Western blotting results was obtained with the other groups of patients, although reactivity with one or more of the major polypeptide bands was sometimes seen. Serum from one blood donor, examined by ELISA and Western blotting, was positive. Differences in the methods of antigen preparation and of epitopes recognized by individuals may account for different reactivities in the tests. It is concluded that infections ofE. cuniculiare common in the tropics and that reactivations of these infections might be a hazard to AIDS patients.
The larvicidal activity of cyclosporin A againstSchistosoma mansoniin mice
Authors: Munro G. H. , Brannan L. R. , Chappell L. H. , Thomson A. W. , McLaren D. J.
Published: June 2009

Treatment of BALB/c or MF1 mice with cyclosporin A (CsA) around the time of infection withSchistosoma mansoniconferred almost complete protection. The migration kinetics of L-[75Se]selenomethionine-labelled infective cercariae were investigated by compressed tissue autoradiography. Similar levels of skin penetration were achieved by cercariae in control and drug-treated individuals. CsA arrested 87–94% of the worms in the skin and ultimately all of these died in this site. Few worms (7–14%) migrated from the skin to the lungs and none completed migration to the liver. Nevertheless, the autoradiograms revealed a limited degree of lateral cutaneous migration by the worms present in the skins of CsA-treated mice. Results of perfusion recovery experiments carried out during the course of infection reinforced the tracking data.
Activation and inhibition of the brush-border membrane-bound alkaline phosphatase activity of Hymenolepis diminuta (Cestoda) by divalent cations
Authors: Pappas P. W.
Published: June 2009

In the absence of exogenous divalent cations, the isolated brush-border plasma membrane of Hymenolepis diminuta possesses alkaline phosphatase activity (APA). APA is stimulated in the presence of exogenous Mg2+ and inhibited by low concentrations of Zn2+ or high concentrations of Ca2+, and inhibition of APA by Zn2+ is reversed by both Mg2+ and Ca2+. APA is inhibited by ethylenediamine tetraacetic acid (EDTA), ethyleneglycol-bis-(β-aminoethyl ether) N, N′-tetraacetic acid, and 1, 10-phenanthroline in time- and concentration-dependent fashions, with EDTA being the most effective inhibitor. Following treatment with EDTA, APA is restored by Mg2+ and, to a lesser extent, by Ca2+, but not by Zn2+. Thus, APA represents a Mg2+-dependent enzyme that can be partly activated by Ca2+ but only in the absence of Mg2+.
Large-scale production ofPlasmodium vivaxsporozoites
Authors: Ponnudurai T. , Lensen A. H. W. , van Gemert G. J. , Bolmer M. , van Belkum A. , van Eerd P. , Mons B.
Published: June 2009

Mass-scale production ofPlasmodium vivaxsporozoites inAnopheles stephensiwas achieved using the chimpanzee (Pan troglodytes) as a source of infective blood. Membrane feeding was as successful as feeding mosquitoes directly on the animal so long as the time between drawing the blood and feeding was restricted to 45 min. Longer delays such as 2–3 h resulted in loss of infectivity in terms of oocyst production. The selected strain ofA. stephensiwas highly susceptible toP. vivax(Chesson strain). A strain ofA. stephensirelatively refractory toP. falciparumshowed no cross-refractoriness toP. vivax. Mixed infections ofP. falciparumandP. vivaxdid not interfere with each other in their development inA. stephensi. A second normal blood meal to mosquitoes infected withP. vivaxincreased the yield of salivary gland sporozoites.
Genomic divergence in the ecologically differentiated English freshwater and marine strains of Pomphorhynchus laevis (Acanthocephala: Palaeacanthocephala): a preliminary investigation
Authors: Munro M. A. , Reid A. , Whitfield P. J.
Published: June 2009

In and around the British Isles, three biologically specialized strains of the fish acanthocephalan Pomphorhynchus laevis have been recognized, each differing in geographical distribution and both final and intermediate host utilization. Six restriction endonuclease digests of the genomic DNA of the English freshwater and marine strains were compared by genomic cross-hybridization using the randomly sheared and radio-isotope labelled genomic DNA of freshwater P. laevis, and also by using a heterologous isotope labelled ribosomal DNA probe. Autoradiographs of hybridized Southern blots provided evidence for considerable homogeneity in the total repetitive DNA of the two strains as well as some preliminary evidence for possible restriction fragment length polymorphisms using EcoR I and Pvu II.
Action of cyclosporin A on the tapewormHymenolepis diminutain mice
Authors: Wastling J. M. , Gerrard D. , Walker J. , Chappell L. H.
Published: June 2009

Cyclosporin A (CsA), administered in 5 daily subcutaneous doses of 50 mg/kg to MF1 mice immediately following infection withHymenolepis diminutaenhanced parasite growth relative to controls. Drug administered at 24 h intervals for 10 days, and thereafter every 48 h to MF1 and CBA/Ca mice infected withH. diminuta, increased worm survival and growth, delayed host-mediated expulsion of the parasite and enabled some worms to develop to patency. Worm survival and weight both increased in a dose-dependent manner following daily CsA treatment of infected CBA/Ca and BALB/c mice (0–150 mg/kg CsA/day). Delay in parasite elimination was accompanied by increased frequency of worm-attachment in the anterior small intestine (MF1 mice given 5 daily doses of CsA [0–150 mg/kg] following infection); posteriad migration of worms was restricted in a dose-dependent manner. The data presented contrast markedly with the action of the same drug onH. microstomain mice. Thus CsA treatment acts in opposing ways on two closely related parasites in the same host; this possibly reflects the mechanistic antagonism between immunosuppression and anthelmintic activity. This paper reports the first use of a specific T cell-suppressive drug onH. diminutain the mouse, implicating the role of T cells in protective immunity to this parasite.
Modulation of the activity of the internal defence system of the pond snail Lymnaea stagnalis by the avian schistosome Trichobilharzia ocellata
Authors: Amen R. I. , Baggen J. M. C. , Bezemer P. D. , Jong-Brink M. De
Published: June 2009

Effects of infection with the avian schistosome Trichobilharzia ocellata on the activity of the internal defence system of the intermediate snail host Lymnaea stagnalis were studied, utilizing an in vitro phagocytosis assay for determining haemocyte activity. A distinction was made between plasma- and cell-associated effects. The period immediately after penetration of the parasite into the snail host (1.5–72 h post-exposure (p.e.)) was extensively studied. In addition, several time-points coinciding with the later–successive–stages of parasite development (2, 4, 6, 8 and 10 weeks p.e.) were investigated. Plasma-associated enhancement of defence activity was found between 1.5 and 6 h p.e., followed by plasma-associated suppression between 12 and 72 h p.e. A cell-associated activation was found between 1.5 and 6 h p.e. and also at 8 and 10 weeks p.e. How these effects on the defence system may be related to phenomena observed in infected snails at these time-points is discussed.
Identification and characterization of two repetitive non-variable antigens from African trypanosomes which are recognized early during infection
Authors: Müller N. , Hemphill A. , Imboden M. , Duvallet G. , Dwinger R. H. , Seebeck T.
Published: June 2009

The present paper describes two repetitive proteins representing common antigens of African trypanosomes which are non-variant and which are recognized early in infection by the host immune system. These antigens were identified by their ability to immunoreact with bovine serum taken during the early phase of a cyclic trypanosomal infection. Screening of a cDNA library fromT. b. gambiensewith such early infection serum identified a protein which contains a repetitive motif consisting of 68 amino acid repeat units (GM6). Immunofluorescence and immunogold electron microscopy revealed that GM6 is located on fibres which connect the microtubules of the membrane skeleton with the flagellum. A second repetitive antigen detected by this serum is MARP1 (microtubule-associated repetitive protein 1), a protein previously characterized in this laboratory as a high-molecular weight component of the membrane skeleton, which consists of more than 50 tandemly repeated, near-identical 38 amino acid repeat units. Beta-galactosidase fusion products of both proteins demonstrated a strong immunoreactivity with sera fromT. b. bruceiandT. congolense-infected cattle. The result from this preliminary immunological evaluation indicates a high immunodiagnostic sensititivy (90%) of the two recombinant antigens which make them interesting candidates for immunodiagnosis of trypanosomiasis in cattle.
Measurement of Ascaris lumbricoides infection intensity and the dynamics of expulsion following treatment with mebendazole
Authors: Forresteer J. E. , Scott M. E.
Published: June 2009

Intensity of Ascaris lumbricoides infection was measured in terms of egg counts and worm burden in children 2–10 years of age. The expulsion of A. lumbricoides with a 3-day treatment of mebendazole occurred over 8 days, beginning on the second day of treatment. Ninety-seven percent of the worms were expelled between the second and seventh days. A rapid means of estimating eggs per gram (epg) by the Kato Katz technique correlated well with the method described by Martin & Beaver (1968). In spite of apparent density dependence in egg production, A. lumbricoides egg counts correlated well with worm burdens. It is concluded that, within the context of community surveys, epg is a reasonable means of identifying heavily infected individuals and that epg can be estimated rapidly by a slight modification to the standard Kato Katz technique.
Antibody to carbohydrate and polypeptide epitopes on the surface of schistosomula ofSchistosoma mansoniin Egyptian patients with acute and chronic schistosomiasis
Authors: Omer Ali P. , Mansour M. , Woody J. N. , Smithers S. R. , Simpson A. J. G.
Published: June 2009

125I-Schistosoma mansonischistosomulum surface antigens were immunoprecipitated with human antibodies from individual Egyptian patients diagnosed as being either acutely or chronically infected withS. mansoni. Both sets of patients were found to have IgG antibodies in their sera capable of immunoprecipitating the majorMr> 200, 38 and 32K antigens. However, the immunoprecipitation of theMr200K antigen was found to constitute a significantly greater proportion of the total precipitate achieved with acute sera than with chronic sera. TheMr38 and 32K antigens were more variably precipitated by the acute sera than the chronic sera but the proportion of the total precipitation that these two antigens constituted was not found to be significantly different between the two sets of sera. Immunoprecipitation with pooled antibodies absorbed with egg and adult worm homogenates which had been treated to remove either carbohydrate or polypeptide epitopes demonstrated that theMr> 200K antigen was the principal target of egg-cross-reactive anti-carbohydrate antibody amongst the antigens detected. TheMr38 and 32K antigens were found to be precipitated by antibodies to protease-sensitive and periodate-insensitive polypeptide epitopes. These results are consistent with egg-cross-reactive anti-carbohydrate IgG antibody making a greater contribution to schistosomulum surface recognition in acute infection than in chronic infection. Indeed the presence of a higher level of egg-cross-reactive and anti-carbohydrate antibody directed against schistosomulum surface epitopes in an acute serum pool than in a chronic serum pool was confirmed by measurement of antibody binding to whole schistosomula.
Aggregation and stability in parasite—host models
Authors: Adler F. R. , Kretzschmar M.
Published: June 2009

This paper generalizes the two-dimensional approximation of models of macroparasites on homogeneous populations developed by Anderson & May (1978), focusing on how the dispersion (the variance to mean ratio) of the equilibrium distribution of parasites on hosts is related to the stability of the equilibrium. We show in the approximate system that the equilibrium is stabilized not by aggregation, but by dispersion which increases as a function of the mean. Computer simulations indicate, however, that this analysis fails to capture properly the dynamics of the full system, raising the question of whether any two-dimensional system could produce an adequate approximation. We discuss the relevance of our results to several empirical studies which have examined the relation of dispersion to the mean.
The role of mononuclear-cell recruitment to the lungs in the development and expression of immunity toSchistosoma mansoni
Authors: Ratcliffe E. C. , Wilson R. A.
Published: June 2009

The role of pulmonary cellular responses in the induction and expression of immunity toSchistosoma mansonihas been evaluated. From experiments in which mice were challenged at intervals after vaccination, we conclude that the resistance mechanism operating in the lungs develops between days 11 and 20. Injection of51Cr-labelled splenocytes revealed that mononuclear cell recruitment to the lungs, stimulated by the arrival of attenuated schistosomula, intensified progressively between days 10 and 16 post-vaccination. The increased cellularity was reflected in a 19·5% augmentation in the wet-weight index (WW). The period of enhanced cell recruitment therefore coincided with the build-up of resistance. By day 22 post-vaccination infiltration had declined, whilst WW remained elevated. This indicates the persistence of recruited cells, which include schistosome-reactive T lymphocytes, in the lungs. We were unable to demonstrate augmented recruitment of51Cr-labelled cells after challenge of vaccinated mice, but WW rose slightly, peaking on day 12. Although clearly of a lower order than the primary response, the secondary response was more rapid, implying the existence of immunological memory. These results accord with the concept that schistosome-reactive T lymphocytes recruited after vaccination ‘arm’ the lungs against the arrival of challenge parasites.
A comparison of the sites of acid phosphatase activity in an adult filaria, Setaria sp. and in some gastro -intestinal nematodes
Authors: Maki Jun , Yanagisawa Toshio
Published: June 2009

The histochemical localization of acid phosphatase in an adult filaria, Setaria sp. obtained from the peritoneal cavity of a cow was closely examined and compared with that of adult nematodes parasitic in the host alimentary canal; special attention was paid to the intestine and body wall of the parasites. Setaria sp. was found to show high acid phosphatase activity in the interchordal hypodermis of the body wall and uterine microfilariae, and similar activity is suspected to occur in the cuticle. The intestine of this nematode exhibited very low, if any, activity. In contrast, nematodes parasitic on the alimentary canal, such as Toxocara cati, T. canis, Physaloptera sp. and Ancylostoma caninum, showed no activity in the body wall and very high activity in the luminal surface of their intestine. The possible function of the abundant acid phosphatase in the body wall of this filaria is discussed.
Prospects for the biological control of plant-parasitic nematodes
Authors: Tribe H. T.
Published: June 2009

Biological control is understood here in the classical sense, which is precisely defined by De Bach (1964) as ‘the action of parasites, predators or pathogens in maintaining another organism's population density at a lower average than would occur in their absence’. This account consists of a survey of the principal causes of disease in nematodes, with a summary of the efforts made to use certain pathogens in practise and a discussion of nematode pathology with reference to destruction of plant pathogenic nematodes.
Characterization of buffalo-derived theilerial parasites with monoclonal antibodies and DNA probes
Authors: Conrad P. A. , Ole-Moiyoi O. K. , Baldwin C. L. , Dolan T. T. , O'Callaghan C. J. , Njamunggehr R. E. G. , Grootenhuis J. G. , Stagg D. A. , Leitch B. L. , Young A. S.
Published: June 2009

The characteristics of intra-lymphocyticTheileriaisolated from African buffalo and from cattle that were infected with buffalo-derived parasites were evaluated using anti-schizont monoclonal antibodies (mAbs) and DNA probes. Antigenic differences were revealed by the reactivities of 27 mAbs with the buffalo-derived parasites isolated from different animals. Antigenic diversity was also seen withTheileria-infected lymphoblastoid cell isolates taken from the lymph nodes and blood of the same animals. Two DNA probes, selected from a genomic library ofT. parvapiroplasm DNA cloned inλgt11, showed specific hybridization to parasite DNA in Southern blots of restriction enzyme-digested, lymphoblastoid cells infected with buffalo-derived theilerial parasites. Genotypic differences between the buffalo-derived parasites were revealed by the restriction fragment length polymorphisms seen with hybridization of those probes to DNA from cloned and unclonedTheileria-infected cell lines. The evaluation of theilerial parasites derived from buffalo and from cattle which underwent typicalT. p. lawrenceireactions, after being infected with buffalo-derived theilerial parasites, did not show any specific phenotypic or genotypic characteristics of these parasites that would distinguish them fromT. p. parvaandT. p. bovisparasites. The validity of these subspecies distinctions is discussed.
The prevalence and pathology of Schistosoma nasale Rao, 1933 in cattle in Sri Lanka
Authors: De Bont J. , Van Aken D. , Vercruysse J. , Fransen J. , Southgate V. R. , Rollinson D.
Published: June 2009

During 1987 a total of 1393 cattle was examined for Schistosoma nasale infection at the Kandy slaughterhouse, Sri Lanka. The overall prevalence was 12·6% (monthly range 3–17%). Based on the appearance of macroscopic lesions, 6 types (0–5) were recognized; type 5 being the most severe, with cauliflower-like growths obstructing the nasal cavity. Older bovines with 8 permanent incisors were more heavily infected (29·%) than younger ones with no permanent incisors (6·0%). The severity of the lesions increased also with the age of the animals. Observations on the localization of the lesions showed that the first sessile nodular areas appear on the medial septum, on the dorsal edge of the ventral nasal concha and on the lateral wall of the middle meatus of the nasal cavity. Later, they gradually spread over the whole mucosal surface of the anterior part of the cavity but were rarely found further than 10 cm posterior to the nasal opening. The histopathology showed that granuloma formation due to the presence of eggs was the most common feature of the respiratory mucosa.
Ancylostoma ceylanicum in the hamster: observations on the host—parasite relationship during primary infection
Authors: Garside P. , Behnke J. M.
Published: June 2009

The course of primary infection with a hamster-adapted strain of Ancylostoma ceylanicum was studied in inbred DSN and randomly bred WO/GD and WO/CR hamsters. Infective larvae were administered orally and began to develop in the small intestine without embarking on a tissue migration. Only the occasional larva was detected in other organ sites. It was concluded that the developing larvae moulted on days 3–4 and again to the pre-adult stage about 9–11 days post-infection. Worm burdens in infected hamsters were stable for at least 11 weeks after infection. There was no sudden expulsive phase and some adult worms survived for over 200 days. Overall the sex ratio of worms in groups of hamsters killed concurrently was about 50% although occasionally the ratio was biased in favour of one sex in individual animals. The blood packed cell volume (PCV) was significantly depressed 2 weeks following infection and continued to decline until a point of stability was achieved 4–5 weeks post-infection. The PCV subsequently remained depressed throughout the period of observation. Infected hamsters lost weight if kept in groups, but not when housed in separate cages. Groups of animals which lost weight did not recover to normal values within 11 weeks of infection. It is suggested that this model of hookworm infection has scope for exploring aspects of the host-parasite relationship which the canine models cannot fulfill adequately.
Intra-erythrocytic death of the parasite in mice recovering from infection withBabesia microt
Authors: Clark I. A. , Richmond J. E. , Wills E. J. , Allison A. C.
Published: June 2009

As mice recover from infection withBabesia microti, abnormal forms of the parasite are present in some red cells. These forms are non-infective, indistinguishable by light microscopy from those present after treatment with amicarbalide, a babesicidal drug, and persist in splenectomized mice.

Electron microscopy confirmed that these abnormal forms are degenerating intra-erythrocytic parasites. In the absence of evidence for death ofB. microtielsewhere in the body, it appears that infections of mice with this parasite are normally terminated by their death within circulating red cells. This has important implications for the mechanism of immunity to both this parasite and thosePlasmodiumspp. with which it cross-protects in this host.
Immunodepression inBabesia microtiinfections
Authors: Purvis Anne C.
Published: June 2009

Infection with the avirulent piroplasmBabesia microtiin mice is accompanied by a marked depression in the ability of the mice to mount an immune response to sheep red blood cells. The period of immunodepression begins 3 days after peak parasitaemia and is maximal 4 days later. There-after, there is a slow return to normal immune responsiveness, correlated with the gradual disappearance of the parasites from the blood. Both IgM and IgG responses are depressed. Cell-mediated responses as determined by contact sensitivity to oxazolone and allograft survival are apparently unaffected. Phagocytic activity as measured by carbon clearance tests is increased, and is correlated with the parasitaemia.
Frequency distribution of Brugia malayi microfilariae in human populations
Authors: Srividya A. , Krishnamoorthy K. , Sabesan S. , Panicker K. N. , Grenfell B. T. , Bundy D. A. P.
Published: June 2009

This study examines the effects of host age and sex on the frequency distribution of Brugia malayi infections in the human host. Microfilarial (mf) counts for a large data base on the epidemiology of brugian filariasis in Shertallai, Kerala, South India are analysed. Frequency distributions of microfilarial counts partitioned by age are successfully described by zero-truncated negative binomial distributions, fitted by maximum likelihood. This analysis provides estimates of the proportion of mf-positive individuals who are identified as negative due to sampling errors, allowing the construction of corrected mf age–prevalence curves, which indicate that the observed prevalence may under-estimate the true figures by between 18 and 47%. There is no evidence from these results for a decrease in the degree of over-dispersion of parasite frequency distributions with host age, such as might be produced by the acquired immunity to infection. This departure from the pattern in bancroftian filariasis (where there is evidence of such decreases in over-dispersion; Das et al. 1990) is discussed in terms of the long history of filariasis control (and consequently low infection prevalence) in Shertallai.