bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental stages of Cyclospora talpae in the liver and bile duct of the mole (Talpa europaea)
Authors: Mohamed H. A. , Molyneux D. H.
Published: June 2009

The completed life-cycle of Cyclospora talpae, an extra-intestinal coccidian (Apicomplexa) of the liver of the mole (Talpa europaea). is reported. Oocysts sporulated within 12–14 days at room temperature (20–22 °C). Both macro- and micro-gametocytes developed independently within the nucleus of epithelial cells lining the bile duct as demonstrated by both light and electron microscopy. Merogony was seen in the mononuclear cells in the capillary sinusoids of the liver. Merozoites showed the typical ultrastructural features of the Apicomplexa. The life-cycle of C. talpae and the ultra-structure of the gametogonic and merogonic stages are reported; the ultrastructure of the merozoites is reported as the first description of this stage for the genus Cyclospora.
Epidemiological significance of vector–parasite interactions
Authors: Dye C.
Published: June 2009

A great deal of published experimental evidence shows that parasite-induced changes in host choice, and biting and survival rates of bloodsucking insects are an important source of bias in estimates of Vectorial Capacity. I argue here that, because of the difficulties of handling these and other biases in practice, indices (based on the Vectorial Capacity) which purport to measure transmission rate are best used in a comparative rather than an absolute way. They should attempt to measure, not transmission rate, but changes in transmission rate. In this case, the less restrictive assumption that parasites are responsible for constant bias (rather than no bias) leads to relatively small errors. The results encourage a more optimistic view of the performance of classical entomological indices such as the parous rate. They should also help to redirect the principal epidemiological question about vector–parasite interactions: future studies should be concerned with the impact of parasites, not directly on Vectorial Capacity, but on the comparative measures which are actually used to evaluate transmission rate.
Hymenolepis diminuta (Cestoda) liberates an inhibitor of proteolytic enzymes during in vitro incubation
Authors: Pappas P. W. , Uglem G. L.
Published: June 2009

Hymenolepis diminuta liberated measurable amounts of ‘Lowry-positive material’ (LPM) and protein during incubation for 2 h in vitro. When tapeworms were incubated in the presence of bovine trypsin (BT), or when BT was added to the medium after removing the tapeworms, the enzyme's proteolytic activity was inhibited significantly. Centrifugation of the medium at 30 000 g yielded a pellet composed of tegumental elements, but this fraction did not inhibit BT. The 30 000 g supernatant fraction contained a chemical(s) that inhibited the proteolytic enzymes of the rodent host's intestinal contents (IC). The inhibitor(s) was stable following repeated freeze-thaw cycles, heat labile, and not degraded by BT or IC, and it inhibited the amidase activity of BT in a non-competitive manner.
Immunodiagnosis of taeniasis by coproantigen detection
Authors: Allan J. C. , Avila G. , Noval J. Garcia , Flisser A. , Craig P. S.
Published: June 2009

Immunodiagnostic tests for Taenia-specific faecal antigen based on polyclonal rabbit antisera against Taenia saginata or Taenia solium proglottid extracts in capture-type ELISA assays have been developed. Taenia-specific antigen was detected in detergent-solubilized faecal extracts from T. solium- and T. saginata-infected hosts. Coproantigen from T. solium-infected hamsters did not cross-react with faeces from rodents infected with Hymenolepis diminuta, H. citelli, H. micro-stoma, Necator americanus, Strongyloides ratti or Nematospiroides dubius and faeces from uninfected animals. When the T. saginata-capture ELISA was tested with faecal samples positive for T. solium antigen, no cross-reactions were obtained. However, faecal samples from humans infected with T. solium or T. saginata, including some with extremely low egg counts, were cross-reactive by either test. Nevertheless, considerably higher O.D. values were obtained with stool samples from Taenia patients compared to Hymenolepis nana-infected or uninfected individuals. Two individuals, infected with Taenia sp. and positive for coproantigens by ELISA, became antigen-negative 6 days after treatment with Niclosamide. The possibility of developing species-specific immunodiagnostic tests for human taeniasis through coproantigen detection is discussed.
Numerical taxonomy of Trypanozoon based on polymorphisms in a reduced range of enzymes
Authors: Stevens J. R. , Godfrey D. G.
Published: June 2009

Numerical analyses of Trypanozoon taxonomy are presented, based on the isoenzyme data of Stevens et al. (1992). The previous study used a reduced range of enzymes compared with earlier work; the analyses indicate the value of this rationalized system. Both recently isolated trypanosome stocks and previously studied populations were included, allowing detailed comparison with earlier studies. Relationships between zymodemes were calculated with an improved similarity coefficient program, using Jaccard's coefficient (1908), and by Nei's method (1972). Dendrograms were constructed from the matrices produced with the group-average method. The groupings produced by both numerical methods were in close agreement, and the clusters of related principal zymodemes largely matched the species, subspecies and strain groups proposed by previous workers. Trypanozoon biochemical taxonomy is reviewed and the groupings reinforced by this study are: the mainly East African strain groups, busoga, zambezi, kakumbi, kiboko and sindo; T.b. gambiense and the bouaflé strain group from West Africa, and T. evansi; an intermediate bouaflé/busoga group was also recognized.
Integration and expression of murine retrovirus-related sequences in schistosomes
Authors: Tanaka M. , Iwamura Y. , Amanuma H. , Irie Y. , Watanabe M. , Watanabe T. , Uchiyama Y. , Yasuraoka K.
Published: June 2009

Antibodies against the retrovirus envelope glycoprotien (gp70) of mouse xenotropic retrovirus, BALB virus 2 (Bv2) reacted with the adult worms ofSchistosoma japonicumandS. mansoni. This reaction was completely inhibited after adsorption of the antibodies with virions of retrovirus. The reactive schistosome antigen was located in the subtegumental layer of the adult male fluke and in the vitelline gland of the adult female ofS. japonicumandS. mansoni. Proteins extracted from both parasites were examined by immunoblot analysis. Anti-Bv2 gp70 antiserum reacted with those proteins from both schistosomes and the band patterns were different among sexes and species. Southern hybridization of the DNA extracted from adults ofS. japonicumandS. mansonidemonstrated the presence of sequences homologous to theenvgene of mouse ecotropic and xenotropic retroviruses. DNA sequences homologous to thegagandpolregions of the ecotropic murine leukaemia virus were also detected in the DNAs of schistosomes
On the interpretation of age—prevalence curves for schistosome infections of host snails
Authors: Woolhouse M. E. J.
Published: June 2009

The prevalence of schistosome infections in intermediate host snails varies with snail age. The relationship between age and prevalence, the age—prevalence curve, is complex and may vary in space and time, and among parasite—host species. Field studies show that the shape of the age—prevalence curve may be seasonally variable, and that at some times there may be a decline in prevalence among older snails. This paper attempts to explain these observations in terms of the underlying epidemiological processes. A discrete-time version of Muench's catalytic model for age-dependent infection is developed. Model simulations were carried out using life-history and epidemiological parameters derived from studies ofSchistosoma haematobium—Bulinus globususin Zimbabwe. Analysis of model behaviour identifies aspects of the schistosome— snail interaction that affect the shape of the age—prevalence curve. The following features can result in a decline in prevalence among older snails. (1) A decrease in the survival rate of patent infected snails with age. (2) A decrease in the force of infection with age. (3) A high rate of loss of infection. (4) A heterogeneity in the snail population such that the probability of infection is correlated with snail fecundity. (This would occur if there existed a spatial correlation between force of infection and fecundity, or if there were a correlation between fecundity and susceptibility.) The evidence for the occurrence of these features in the field is assessed. Survival rate is related more closely to the duration of patent infection than to ageper se. The evidence for age-dependent force of infection is equivocal. Significant loss-of-infection rates have yet to be demonstrated. Heterogeneities in force of infection and fecundity have been reported and, for the Zimbabwe data, this mechanism can explain seasonally in the age—prevalence curve as a function of known seasonal variation in the force of infection and snail fecundity.
Infectivity of Trichinella isolates in mice is determined by host immune responsiveness
Authors: Bolas-Fernandez F. , Wakelin D.
Published: June 2009

A comparison was made of the development, survival and reproduction of 5 isolates of Trichinella spiralis in inbred mice. Low responder C57BL/10 mice allowed worms of all isolates to survive longer and reproduce more successfully than did high responder NIH mice, suggesting that host immunity exerted a dominant influence upon infectivity. One isolate (Is-5 (W) — an arctic isolate) had a markedly lower infectivity than all other isolates, and was selected for more detailed study, together with isolate Is-1 (S) (a temperate isolate) which showed high infectivity. The lower infectivity of Is-5 (W) reflected a more rapid onset of immunity in mice infected with this parasite, immunity reducing the reproductive potential of female worms and causing an early expulsion from the intestine. No evidence of a dose-dependent suppression of immunity was found to explain the higher infectivity of Is-1 (S). Is-5 (W) provided a very rapid mucosal mastocytosis in infected mice, whereas Is-1 (S) caused no measurable response. In contrast, Is-1 (S) elicited higher levels of circulating parasite-specific antibodies than did Is-5 (W). These results are discussed in relation to the interplay of parasite immunogenicity and host immune responsiveness in determining infectivity, and point to the importance of identifying those immunodominant parasite molecules which control the balance of the host—parasite relationship.
Growth of single proglottides during early adult development of Hymenolepis nana
Authors: Kumazawa H. , Fairweather I.
Published: June 2009

The growth of individual proglottides of Hymenolepis nana has been studied by measuring the width and length of the proglottides between days 3 and 8 post-infection in mice. Two sets of measurements were obtained. The first involved proglottides immediately posterior to the point of proglottis formation and proglottides at particular stages of development. For the second set, measurements were made of proglottides at certain positions in the worm, specifically the 20th, 100th and 200th proglottides, as counted from the posterior end of the worm. For proglottides at different stages in development, the width of a particular stage was greater in the later days of infection, while the length was almost constant. The length of newly-formed proglottides varied only slightly with time despite differences in the width and in the 3-fold increase in proglottis production that occurs between days 3 and 8 post-infection. The width of the 20th, 100th and 200th proglottides followed parallel growth curves that coincided with each other after an appropriate shift along the time axis. The more anterior the position of the proglottis, the greater was the width at the time of proglottis formation, and so its growth began later on the common growth curve. Growth in length of the 20th proglottis was at first faster than the 100th and 200th proglottides, but later slowed down to a level comparable with them, and the growth curves for the length of the three proglottides were very similar to each other. The rates of growth in the volume of the three proglottides were also estimated. The results are also discussed in relation to other approaches to the study of tapeworm growth and to factors that may be responsible for the growth patterns observed.
Human host selection by anophelines: no evidence for preferential selection of malaria or microfilariae-infected individuals in a hyperendemic area
Authors: Burkot T. R. , Narara A. , Paru R. , Graves Patricia M. , Garner P.
Published: June 2009

Host selection among humans by Anopheles punctulatus was studied in an area of Papua New Guinea endemic for malaria and filariasis. Blood films were made from the stomach contents of freshly engorged mosquitoes found resting on the walls of houses in which the parasite status of the occupants was known. Engorgement rates on humans were non-random but could not be consistently related to the parasite status of individuals in the houses for either malaria or filaria. In some households, anophelines preferentially fed on parasitaemic individuals while in other households aparasitaemic individuals were significantly more often selected. This finding is believed to reflect the fact that malaria and filarial infections in this endemic area are predominantly asymptomatic. There were no significant differences in axillary temperatures between malaria or microfilariae positive or negative individuals.
Diversity patterns in helminth communities in common gulls,Larus canus
Authors: Kennedy C. R. , Bakke T. A.
Published: June 2009

The parameters of species richness, abundance and diversity of the intestinal helminth infracommunities of a sample of 269 Common gulls,Larus canus, were examined over one season at Agdenes, Norway. The communities developed rapidly in unfledged gulls and the diversity parameters were of similar magnitude in immature and adult birds. All parameters were low in the early part of the season, reached maxima in June or July and fluctuated erratically or declined thereafter. Comparison of summary parameters with those from other species of gulls indicated that helminth community diversity in Common gulls is fairly typical of gulls in general. In gulls as a group, helminth communities show common features of high species richness, low abundance, few or no core species and a number of species that occur rarely and in low numbers. Expectations of particularly high parasite community diversity were not fully realised because species lists and diversity of the component community are not a very good basis for predicting diversity at the infracommunity level.
Preliminary biochemical characterization of ‘veil’ structure purified fromTheileria sergenti-, T. buffeli- andT. orientalis-infected bovine erythrocytes
Authors: Sugimoto C. , Kawazu S. , Sato M. , Kamio T. , Fujisaki K.
Published: June 2009

A structure called ‘veil’ inTheileria sergenti-, T. buffeli- orT. orientalis-infected bovine erythrocytes was purified from erythrocyte lysates by Percoll density-gradient centrifugation. On electron microscopical examination, the veils consisted of electron-dense material showing a periodicity of striations and were not surrounded by membranes. Analyses of veil proteins by one- and two-dimensional polyacrylamide gel electrophoresis revealed that the veils contain haemoglobin and several other basic proteins of molecular weight ranging from 15·5 to 46 kDa. By comparing the protein patterns of the veil with those of purified piroplasms and uninfected bovine erythrocytes, these basic proteins appeared to be of parasite origin. It would appear likely that the veils formed by intra-erythrocytic precipitation of haemoglobin and proteins excreted by the parasites. Differences in veil constituents were found betweenT. sergenti, T. buffeliandT. orientalis.
Relationship between body size of adult Anopheles gambiae s.l. and infection with the malaria parasite Plasmodium falciparum
Authors: Lyimo E. O. , Koella J. C.
Published: June 2009

The influence of adult female body size of Anopheles gambiae s.l. on development of midgut and salivary gland infections by the parasite Plasmodium falciparum was investigated in a field study carried out in Tanzania. The proportion of mosquitoes infected during a blood meal was independent of size. However, the number of oocysts harboured by infected mosquitoes increased with size of the mosquito. The proportion of mosquitoes with sporozoites, and thus potentially infective to humans, was highest in intermediate-sized mosquitoes, whereas the largest and smallest mosquitoes were less likely to have sporozoites. This pattern is interpreted as a combination of high survival rate of large, uninfected mosquitoes and of low survival rate of mosquitoes infected with many oocysts.
The effect of repeated chemotherapy on age-related predisposition to Ascaris lumbricoides and Trichuris trichiura
Authors: Chan L. , Kan S. P. , Bundy D. A. P.
Published: June 2009

This study examines the persistence of predisposition to Ascaris lumbricoides and Trichuris trichiura during repeated chemotherapy in an urban community in Kuala Lumpur, Malaysia. Significant predisposition was observed over 2 periods of reinfection with and without age-standardization of data. Analysis of different age groups indicated that predisposition was most strongly detectable in the younger age classes. The intensities of infection with both parasites were strongly correlated at each cycle of intervention, suggesting that individuals were similarly predisposed to both species.
Schistosoma mansoni: the ultrastructure of the ducts of the male reproductive system.
Authors: Otubanjo Olubunmi A.
Published: June 2009

The reproductive duct of the male blood fluke Schistosoma mansoni is relatively short and undulating, extending from the most posterior testis to the beginning of the gynecophoric canal. The reproductive duct may be divided into 3 main regions which differ in ultrastructure; the vas efferens/deferens, the seminal vesicle and the cirrus tube. The epithelium of the vas efferens/deferens consists of a single layer of elongate cells with abundant convoluted lamellae on their apical surfaces. The wall of the seminal vesicle and the cirrus tube are tegumentary in nature. The basic similarities in structure of the surface tegument, the seminal vesicle and the cirrus tube suggest a common embryological origin. The presence of complex lamellae on the luminal surface suggests that the vas efferens and deferens have secretory and possibly nutritive functions apart from temporarily storing developing germ cells. The primary function of the seminal vesicle appears to be that of sperm storage; while the cirrus tube with its complex infolded wall is extensible for insemination. The presence of abundant concentrically distributed sensory papillae around the male genital pore may assist in the pairing of males and females.
Changes in the structure of the male reproductive system of Nematodirus battus during its rejection from lambs
Authors: Martin Jean , Lee D. L.
Published: June 2009

As the infection progresses in lambs, the developing germ cells of male Nematodirus battus become filled with lysosome-like bodies, electron-dense granules and membrane-bound vesicles, and the organization and division of the gametic nucleus appears to be altered. The epithelial cells of the reproductive tract are also damaged and the secretory-type globules produced by the cells of the vas deferens are denatured. These changes are compared with ultrastructural changes observed in other species of nematode affected by the immune response of their hosts.
Infectivity of cultured Plasmodium falciparum gametocytes to mosquitoes
Authors: Ponnudurai T. , Lensen A. H. W. , Van Gemert G. J. A. , Bensink M. P. E. , Bolmer M. , Meuwissen J. H. E.TH.
Published: June 2009

Various factors that may influence routine and high levels of mosquito infection with cultured Plasmodium falciparum gametocytes are considered in this paper. One of the most important is the choice of an appropriate isolate, with facilities for cryopreservation and a good technique for initiation of cultures. The use of automated culture systems with strict adherence to detail and routine has eliminated much of the variability. The quality of the serum used for the culture of gametocytes and inclusion in the feed material for mosquitoes is of the highest importance. Blood collection for culture purposes must preferably involve alcohol as an antiseptic for cleaning donor skin or suitable receptacles. Mosquito blood meals should not include plasma with citrate phosphate dextrose or sera collected in microtainer tubes or from volunteers on proguanil-chloroquine prophylaxis. Sera of individuals on chloroquine alone do not influence transmission. Haemato-crits of from 5 to 10% permit the culture of equally infective gametocytes. It was impossible to predict the outcome of an infection in mosquitoes based on the number of female gametocytes or gametes. Within any experiment, the oocyst load initially increased, followed by a decline with progressively lower numbers of gametocytes accompanied by a progressive increase in the efficiency of transmission. Some of the variability of mosquito infection within an experiment was due to individual differences in the speed of blood digestion of the mosquitoes. A new membrane feeder is described with three different sizes to accommodate a variety of goals. The new design permitted more mosquitoes to feed within a limited period compared to the older more widely used feeder of equivalent capacity, and mosquitoes feeding on the new-type feeder were frequently better infected than those fed on the older type.
The anticoccidial effects of amprolium, dinitolmide and monensin against Eimeria maxima, E. brunetti and E. acervulina with particular reference to oocyst sporulation
Authors: Joyner L. P. , Norton C. C.
Published: June 2009

Chicks infected with the Weybridge strains of Eimeria maxima and E. acervulina were not protected by the normal levels of amprolium, but the sporulation of the oocysts was inhibited. With higher drug concentrations, fewer oocysts were produced. E. brunetti was not so markedly affected, although oocyst sporulation was reduced by the higher dosage levels. The effects were not enhanced by the inclusion of ethopabate.

With dinitolmide the phenomenon was not so marked, although oocyats of E. maxima and E. acervulina were reduced in numbers by the normal drug concentration and sporulation was reduced when this level was increased. Much higher drug levels were required to obtain these effects with E. brunetti. Monensin at 120 ppm affected neither oocyst numbers nor their sporulation in any of the species tested. The significance of the effects of anticoccidial drugs on gametogony and sporogony is discussed.
Asymmetric reproductive output by the monogenean Pseudodiplorchis americanus
Authors: Tocque K. , Tinsley R. C.
Published: June 2009

Pseudodiplorchis americanus accumulates its entire reproductive output in utero during hibernation of its host, Scaphiopus couchii. Infective larvae are released only during the toads' brief entry into water for breeding. In one host population studied prior to transmission, in S.E. Arizona, adult worms contained 0–326 infective stages; 19% of 178 worms produced 51% of the total larvae. Reproductive output was positively correlated with body length which was considered to reflect worm age; first-, second- and third-year worms produced means of 5, 43 and 96 larvae, respectively. Within second- and third-year cohorts, there was a density-dependent reduction in offspring numbers. Under controlled laboratory conditions, the mean rate of offspring accumulation during the first 6 months of development was significantly reduced only in burdens in excess of those found naturally (36–68 worms). In older parasites, a density-dependent reduction in the mean accumulation rate occurred in burdens of 20–32 worms, where 88% of parasites produced offspring at less than half the maximum rate. The asymmetry in individual reproductive output increased with competition and there were significant reductions in the median rates of offspring accumulation at smaller burdens (17–25 and 5–14 worms, in experimental and natural infections, respectively) than evident from decreases in the mean. Thus, individual variation is a more sensitive measure of competition than is the mean.
Effect of the sulphydryl reagent, mersalyl acid, on sex pheromone reception by Heterodera schachtii (Nematoda: Heteroderidae) males
Authors: Aumann J.
Published: June 2009

Female sex pheromone reception was inhibited in a bioassay by treating males of the beet cyst nematode, Heterodera schachtii, with the sulphydryl reagent, mersalyl acid. This effect was blocked by the sulphydryl group protectant, dithiothreitol, indicating the occurrence of sulphydryl groups in the receptor molecules and a role for sulphydryl groups in pheromone reception.
Ultrastrucural observations on the interactionin vitrobetween bovine eosinophils and juvenileFasciola hepatica
Authors: Glauert Audrey M. , Lammas D. A. , Duffus W. P. H.
Published: June 2009

This ultrastructural study has shown that there is a layer of dense flocculent material on the surface of juvenileFasciola hepaticaincubatedin vitrowith specific bovine antiserum. This material corresponds to the complexes of secreted glycocalyx and bovine antibody previously characterized by fluorescence microscopy. Bovine eosinophils attach closely to those regions of the parasite's surface that are free of flocculent precipitates. This close attachment is followed by degranulation of the eosinophils into the narrow zone between the cells and the parasite. Only in these regions is damage, in the form of vacuolation of the tegument, seen within the juvenileF. hepatica. It is concluded that the inability of bovine eosinophils to kill juvenileF. hepaticain the presence of specific antiserum results from the presence of a protective layer, consisting of antigen/antibody complexes, on the parasite's surface.
Pyrolysis gas-liquid chromatography of the pathotypes of the potato cyst nematodesGlobodera rostochiensisandG. pallida
Authors: Fox P. C. , Atkinson H. J.
Published: June 2009

Curie-point pyrolysis gas-liquid chromatography (PGLC) was used to detect gross chemical differences between the 8 European pathotypes of the potato cyst nematodesGlobodera rostochiensisandG. pallida. No qualitative differences were seen with either flame ionization or flame photometric detection systems, although quantitative differences between pathotypes were detected. Cluster analysis of these differences failed to group the pathotypes into species, but separation of some economically important pathotypes was achieved. The potential of PGLC for nematode identification is discussed.
Observations on the development of the male reproductive system in Gyrodactylus gasterostei Gläser, 1974 (Monogenea, Gyrodactylidae)
Authors: Harris P. D.
Published: June 2009

The development of the male reproductive system in Gyrodactylus gasterostei has been followed using parasites of known age maintained on isolated hosts. The penis develops shortly after the parasite has given birth for the first time (at an age of 24–30 h at 13°C) and the first active spermatozoa appear after 40–50 h. Spermatogenesis occurs more rapidly in G. gasterostei than in any other parasitic flatworm (including those from warm-blooded hosts) in which it has been measured, and the onset of male maturity is further hastened by a reduction in the number of pre-spermatogenic germ cell divisions. Spermatogonia have a diploid chromosome complement of 12, and spermatocytes undergo meiosis to produce haploid spermatozoa. No evidence of aneuploidy in spermatozoa was obtained. Although the development of haploid spermatozoa suggests that sexual reproduction can occur, production of embryos by isolated flukes which lack a mature male system indicates that other means of reproduction may also be employed.
The survival of parasite eggs throughout the soil profile
Authors: Storey G. W. , Phillips R. A.
Published: June 2009

An experiment using lysimeters suggested that the eggs ofTaenia saginataandAscaris lumbricoidessurvive for only a short time when applied to pasture in sewage sludge. However, a subsequent experiment which followed the survival of eggs throughout the soil profile demonstrated that someT. saginataeggs could still be found at 200 days on the soil surface, and that survival increased down the profile. Rainfall is shown to be able to wash eggs into the soil where they may be afforded protection from radiation and desiccation; this may have little epidemiological significance.
Eimeria species which infect the chicken contain virus-like RNA molecules
Authors: Ellis J. , Revets H.
Published: June 2009

There is increasing support for the presence of viruses and virus-like particles inside protozoan cells. This study describes viral-like RNA molecules that have been detected in two species of Eimeria that infect the chicken. The RNA molecule identified in E. maxima has been characterized: subcellular fractionation studies have shown that the RNA is present in the cytoplasm, probably as an abundant ribonucleoprotein that is insensitive to RNAse A treatment. Electron microscopy has demonstrated that this RNA molecule is double stranded. In addition, all E. maxima strains examined so far contain this RNA molecule.
Low-dose oral administration of human interferon alpha can control the development ofTheileria parvainfection in cattle
Authors: Young A. S. , Maritim A. C. , Kariuki D. P. , Stagg D. A. , Wafula J. M. , Mutugi J. J. , Cummins J. M. , Richards A. B. , Burns C.
Published: June 2009

Two natural human interferon alpha preparations, (nHuIFN-μ [Cantell]) and (Nhuifn-μ [ISI]), were used for the oral treatment of cattle experimentally infected withTheileria parva parva.In the first experiment, 8 Friesian bulls were inoculated with a 1 in 10 dilution of a sporozoite stabilate ofT. p. parva(Marikebuni) stock. Four of the cattle were treated daily with 1 international unit/kg body weight (i.u./kg bwt) of nHuIFN-μ (Cantell) from day –2 to day 8 p.i. None of the 4 calves given IFN developed clinical theileriosis, but 3 of the 4 control calves died of theileriosis while the fourth had a mild infection. Three of 4 treated calves and the 1 surviving control calf developed a detectable antibody response toT. p. parvaschizont antigen but, on challenged with a 10-fold higher dose of stabilate, the surviving control animal and only 1 of the 4 treated calves proved to be immune. In a second experiment, 4 groups of 4 calves were inoculated with the same stabilate dilution. Three treatment groups were given either 1 i.u. nHuIFN-μ (Cantell), 1 i.u. nHuIFN-μ (ISI), or 10 i.u. nHuIFN-μ (ISI)/kg bwt from day –2 to day 8 p.i. once daily and the fourth group were controls. Clinical theileriosis occurred in 2 controls, 2 calves given 10 i.u. nHuINF-μ (ISI), 1 calf given 1 i.u. nHuIFN-μ (ISI) and no calves given 1 i.u. nHuIFN-μ (Cantell)/kg bwt. Of these, 2, 1, 0 and 0 cattle died in the respective groups. All the surviving cattle proved to be immune on homologous challenge with 10-fold higher dose of stabilate except the 2 cattle which did not develop high antibody responses. A third experiment using an undiluted challenge ofT. p. parva(Muguga) sporozoite stabilate (10α) on 8 steers. Four steers were treated with 1 i.u. nHuIFN-α (Cantell)/kg bwt and 4 were controls. All calves developed acute theileriosis and the experiment was terminated. Cells of the C2 lymphoblastoid cell line, infected withT. p. parva(Muguga) schizonts, were culturedin vitrowith various concentrations (0-01-100 i.u./ml) of nHuIFN-a (Cantell). The IFN appeared to have no effect on host cell or parasite developmental variables when compared to untreated control cultures.
The population biology of the free-living phase ofHaemonchus contortus
Authors: Smith G.
Published: June 2009

A deterministic model for the demography of the free-living stages ofHaemonchus contortusis described. The model consists of three compartments: the pre-infective stages, comprising the eggs and first- and second-stage larvae combined; third-stage larvae in the faeces; and third-stage larvae on the pasture. The mortality(μj)of each of these stages was a function of temperature (K, where K = (degrees Celsius + 30)/100) of the form,μj= ajexp [xjK] + bjexp [– βjK]. The minimum time to second moult (γ) and the moulting rate thereafter (σ) were also functions of temperature (In [1/γ] = c1+ c2[1/K], and σ =d1exp[d2K] respectively). The rate at which L3 larvae migrated out of the faeces was treated as a constant (0.165/larva/day).
Observations on the morphology of the testis in the larvae ofMoniliformis(Acanthocephala)
Authors: Asaolu S. O.
Published: June 2009

Testes in the male early acanthella ofMoniliformis dubiusare cellular. The testes in the middle and late acanthellae and cystacanth stage also contain individual cells but these are embedded in a compact supporting syncytium which also forms the boundary of the testis. The testes are embedded in the cytoplasmic wall of the ligament sac in the early acanthella but after this stage they become exposed in the cavity of the sac when the surfaces of the testes become covered by a surface coat. Certain cells adjacent to testes primordia in the early acanthella appeared to have formed rudiments of vasa efferentia in the middle acanthella.
Hierarchical order of host cues in parasite foraging strategies
Authors: Lewis E. E. , Grewal P. S. , Gaugler R.
Published: June 2009

The importance of host cues to three species of steinernematid nematodes (Rhabdita: Steinernematidae) with different foraging strategies was compared. We presented host materials to nematodes in series to test responses to combinations of host cues. If a fixed hierarchy of cues is followed during foraging, parasites should respond most strongly to cues offered in natural order. Steinernema carpocapsae, an ambush forager, aggregated at the source of volatile host cues only after attachment to host cuticle. They also parasitized hosts more efficiently after contact with cuticle. Steinernema glaseri, a cruise forager, was unaffected by exposure to combinations of host cues. Steinernema feltiae, a nematode with characteristics of both ambushing and cruising, was affected by cue hierarchies when either contact or volatile cues were presented first. Host-associated materials encountered out of the context may not qualify as host cues for the ambush forager, S. carpocapsae. Perhaps the order in which cues are encountered is more predictable for ambushers than for cruisers. Therefore an ambusher's response to host materials has a more fixed contextual framework.
External monitoring of 203Hg-labelled Dirofilaria immitis microfilariae in mice and dogs
Authors: Lengemann F. W. , Grieve R. B. , Chmielewicz M. , Kallfelz F. A. , Georgi J. R.
Published: June 2009

Microfilariae of Dirofliaria immitis were labelled with 203Hg 2+in vitro and injected into irradiated mice and Beagle dogs. With irradiated mice it was possible to demonstrate microfilariae present in the blood and to detect 203Hg by external counting as long as 28 days after dosing. The 203Hg 2+ label had a half-time of 4–5 days; the amount of stable mercury in the labelling medium strongly influenced the survival of microfilariae in vivo. In dogs, external counting showed the lungs to be a major location of the microfilariae soon after reinjection into the host. Evidence was obtained that labelled microfilariae can circulate; however, the detection of dispersed microfilariae is difficult because of the relative insensitivity of the detecting system. For radiomercury the accumulation of the inorganic form in the liver and kidneys limits the long-term usefulness of 203Hg 2+ as a label if the organism being studied also accumulates in these organs.
Generation and characterization of clonedTheileria parvaparasites
Authors: Morzaria S. P. , Dolan T. T. , Norval R. A. I. , Bishop R. P. , Spooner P. R.
Published: June 2009

A 3-step procedure for cloningTheileria parvaparasites was developed. The first step involved thein vitroinfection of a fixed number of bovine lymphocytes with titrated sporozoites. The cell lines obtained from infections initiated using sporozoite/lymphocyte ratios below 1:100 were then selected for cloning as these contained schizont-infected cells, each of which was derived from infection with a single sporozoite. In the second step, these cell lines were cloned by limiting dilution. As sporozoites infect lymphocytes and transform to induce clonal multiplication, this step produced infected cell lines containing both cloned parasites and cloned lymphocytes. In the third step, the cloned cell lines were used to infect cattle and isolation of the parasite in ticks was made during piroplasm parasitaemia. Finally, sporozoites were harvested from infected ticks and used for further characterization. Sporozoites derived from cloned cell lines ofT. parvaMuguga, Marikebuni, Boleni, Uganda and buffalo-derived 7014 were characterized using monoclonal antibody profiles, DNA restriction fragment length polymorphism detected using repetitive and telomeric probes,in vivoinfectivity and, in one case, cross-immunity studies. Additionally, several distinct schizont-infected lymphocyte clones were isolated from the Muguga, Mariakani and buffalo-derived 7014 stocks. The combined results of the characterization revealed that the cloning procedure selected clones ofT. parvafrom the parental stocks which were known to contain a mixture of genetically different parasite populations. The cloning method and the clones generated will be of value in studies of the biology of the parasite and in elucidating the strain specificity of immune responses in cattle.
Random amplified polymorphic DNA fingerprints of the eight taxa of Trichinella and their comparison with allozyme analysis
Authors: Bandi C. , la Rosa G. , Bardin M. G. , Damiani G. , Comincini S. , Tasciotti L. , Pozio E.
Published: June 2009

Eight taxa have recently been proposed as being encompassed by the genus Trichinella on the basis of allozyme and biological data. In this paper we show that an analogous 8 taxon structure for this genus results from the random amplified polymorphic DNAs (RAPDs). Five 10-mer or 20-mer primers were used under different polymerase chain reaction (PCR) conditions to produce multiband RAPD fingerprints from muscle larvae of 40 isolates of Trichinella spp. The resulting RAPD data were analysed following the numerical taxonomic approach, and the resulting classification was compared to that derived from allozyme data. The agreement found between allozymes and RAPDs, while supporting the polyspecific structure of the genus Trichinella, confirms the potential of RAPDs as a tool for the detection of cryptic species. The selected primers were tested on individual muscle larvae in an attempt to standardize a RAPD assay for the routine identification of the 8 taxa of Trichinella. Only 1 of the 5 primers yielded reproducible fingerprints from the single larvae. Using this primer, the 5 species and the 3 other taxa of the genus Trichinella can be identified in a single assay without the need for massive in vivo parasite production.
Metabolism bySchistosoma mansoniof a new schistosomicide: 2-[(1-methylpropyl)amino]-1-octanethiosulphuric acid
Authors: Penido M. L. O. , Nelson D. L. , Vieira L. Q. , Watson D. G. , Kusel J. R.
Published: June 2009

In order to investigate the mode of action of a new class of schistosomicides, theN-alkylaminoalkanethiosulphuric acids, the ‘outer35S] 2-[(1-methylpropyl)amino]-1-octanethiosulphuric acid was synthesized. Labelling studies of adultSchistosoma mansoniwere performed in infected mice and inin vitroincubations. After a single oral dose of the drug to infected mice, 5 metabolites were detected by thin-layer chromatography in organic extracts of male and female adult schistosomes.In vitrostudies showed that the same compounds were present in organic extracts obtained from adult male and female worms. One of these metabolites was identified by mass spectroscopy as being the dimeric disulphide derivative of the parent labelled thiosulphuric acid.
Molecular genetic analysis ofGiardia intestinalisisolates at the glutamate dehydrogenase locus
Authors: Monis P. T. , Mayrhofer G. , Andrews R. H. , Homan W. L. , Limper L. , Ey P. L.
Published: June 2009

Samples of DNA from a panel ofGiardiaisolated from humans and animals in Europe and shown previously to consist of 2 major genotypes–‘Polish’ and ‘Belgian’–have been compared with human-derived Australian isolates chosen to represent distinct genotypes (genetic groups I–IV) defined previously by allozymic analysis. Homologous 0·52 kilobase (kb) segments of 2 trophozoite surface protein genes (tsa417 and tsp11, both present in isolates belonging to genetic groups I and II) and a 1·2 kb segment of the glutamate dehydrogenase (gdh) gene were amplified by the polymerase chain reaction (PCR) and examined for restriction fragment length polymorphisms (RFLPs). Of 21 ‘Polish’ isolates that were tested, all yieldedtsa417-like andtsp11-like PCR products that are characteristic of genetic groups I or II (15 and 6 isolates respectively) in a distinct assemblage ofG. intestinalisfrom Australia (Assemblage A). Conversely, most of the 19 ‘Belgian’ isolates resembled a second assemblage of genotypes defined in Australia (Assemblage B) which contains genetic groups III and IV. RFLP analysis ofgdhamplification products showed also that ‘Polish’ isolates-were equivalent to Australian Assemblage A isolates (this analysis does not distinguish between genetic groups I and II) and that ‘Belgian’ isolates were equivalent to Australian AssemblageB isolates. Comparison of nucleotide sequences determined for a 690 base-pair portion of thegdhPCR products revealed ≥ 99·0% identity between group I and group II (Assemblage A/‘Polish’) genotypes, 88·3–89·7% identity between Assemblage A and Assemblage B genotypes, and ≥ 98·4% identity between various Assemblage B/‘Belgian’ genotypes. The results confirm that theG. duodenalisisolates examined in this study (inclusive ofG. intestinalisfrom humans) can be divided into 2 major genetic clusters: Assemblage A (= ‘Polish’ genotype) containing allozymically defined groups I and II, and Assemblage B (= ‘Belgian’ genotype) containing allozymically defined groups III and IV and other related genotypes.
Protective immunity toSchistosoma mansoniinduced in the olive baboonPapio anubisby the irradiated cercaria vaccine
Authors: Yole D. S. , Pemberton R. , Reid G. D. F. , Wilson R. A.
Published: June 2009

The radiation-attenuated schistosome vaccine induces a high level of protective immunity in rodents. In order to assess its potential relevance to man, we have tested its efficacy in the non-human primatePapio anubis. A vaccination regime consisting of 3 exposures of approximately 9000 cercariae irradiated with 30 or 60krad. of gamma radiation induced > 50% protection to a challenge with normal larvae. A lower attenuating dose of 20 krad., optimal for vaccination of mice, was less effective. All vaccination regimes elicited a population of PBMC which proliferatedin vitroin response to antigen. These responses peaked after the third exposure but were significantly lower after challenge. They revealed relatively little cross-reactivity with adultSchistosoma haematobiumantigens and provided some evidence for stage-specific antigens. Circulating IgM reactive with adultS. mansoniantigen was detected after the second vaccination but levels remained low throughout. In contrast, IgG levels were boosted by successive vaccinations, although they showed a tendency to decline from 14 days after each exposure. There also appeared to be a lag of about 14 days after challenge before levels began to rise. Thus, both proliferation and antibody data suggest a lower responsiveness after challenge which may reflect either the reduced antigenic load or immunogenicity of normal, compared to vaccinating larvae. The data indicate that the attenuated schistosome vaccine is capable of inducing protection in a highly permissive primate host, with the implication that the mechanisms involved may also be relevant to man.
A vasoactive intestinal polypeptide-like protein excreted/secreted byNippostrongylus brasiliensisand its effect on contraction of uninfected rat intestine
Authors: Foster N. , Lee D. L.
Published: June 2009

The 50–30 kDa fraction isolated from the excretory/secretory products (E/S) of the nematodeNippostrongylus brasiliensissignificantly decreased the amplitude of contraction of segments of uninfected rat intestine when injected into the lumen of the segments maintained in an organ bath. Dot blot analysis of the fraction suggested that it was similar in immuno-reactivity to porcine vasoactive intestinal polypeptide (VIP). When antiserum to porcine VIP was mixed withN. brasiliensisE/S and the mixtures were injected into the lumen of segments of rat intestine, the inhibitory effect of the E/S on amplitude of contraction decreased. When physiological concentrations of porcine VIP (12·9 pmol/ml) were injected into the lumen of segments of uninfected rat intestine the amplitude of contraction decreased significantly. Western blot analysis of the E/S, using antiserum to porcine VIP, recognized a 30 kDa protein in the E/S and also in whole worm homogenate suggesting that synthesis of the peptide occurs inside the nematode. Peptide histidine isoleucine (PHI)-like immuno-reactivity was detected in a 68 kDa fraction of the E/S and the homogenate but this fraction did not affect the amplitude of contractions of the intestine.
Investigations on the presence of an infectious proportion amongst populations ofSteinernema feltiae(Site 76 strain) infective stages
Authors: Bohan D. A. , Hominick W. M.
Published: June 2009

Experimental studies were conducted on the proportion ofSteinernema feltiaeFilipjev (Site 76 strain) infective stages that infectedGalleria mellonellaL larvae, in sand tube assays. A full statistical analysis of the sand assay tubes was also undertaken. The analysis showed that the sand tubes were not a significant source of variation. Consequently the observed behaviour of the infective stages was considered to be due to a biological effect. The study shows that the proportion of infective stages that became parasitic did not increase with increases in the density of applied infective stages, nor did the proportion increase with an increase in the number of hosts. It is argued that these findings are consistent with the presence of a proportion of individual infective stages that are capable of causing infection.
Genetic control of susceptibility toTaenia crassicepscysticercosis
Authors: Fragoso G. , Lamoyi E. , Mellor A. , Lomeli C. , Govezensky T. , Sciutto E.
Published: June 2009

We previously reported that genes within the major histocompatibility complex influence the intensity ofTaenia crassicepsmurine cysticercosis. This genetic control, readily apparent in mice of BALB background, was further studied inH-2congenic and recombinant B10 mice as well as in BALB/c substrains differing in expression of Qa-2 antigens. Similarly low parasite numbers were found in all B10-derived strains infected, regardless ofH-2haplotype, indicating that the effect ofH-2genes in controlling susceptibility is overridden in mice of B10 background. BALB/c substrains differed significantly in susceptibility. BALB/cAnN was highly susceptible, whereas BALB/cJ, in contrast, was highly resistant and BALB/cByJ showed intermediate susceptibility. Susceptibility or resistance in BALB/c substrains may be associated to differences known to distinguish them, such as serum testosterone levels and Qa-2 protein expression. In bidirectional F1 hybrids of C57BL/6J and BALB/cAnN resistance to cysticercosis was inherited as a dominant autosomal trait. In F1 hybrids of BALB/cJ with BALB/cAnN, BALB/cByJ and BALB.K resistance was also inherited as a dominant trait. However, in (BALB/cAnN × BALB/cByJ)F1 and (BALB/cAnN × BALE.K)F1 hybrids, dominant susceptibility to cysticercosis was observed.