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Mark Viney - One of the best experts on this subject based on the ideXlab platform.
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Strongyloides ratti and s venezuelensis rodent models of Strongyloides infection
Parasitology, 2017Co-Authors: Mark Viney, Taisei KikuchiAbstract:Strongyloides spp. are common parasites of vertebrates and two species, S. ratti and S. venezuelensis, parasitize rats; there are no known species that naturally infect mice. Strongyloides ratti and S. venezuelensis overlap in their geographical range and in these regions co-infections appear to be common. These species have been widely used as tractable laboratory systems in rats as well as mice. The core biology of these two species is similar, but there are clear differences in aspects of their within-host biology as well as in their free-living generation. Phylogenetic evidence suggests that S. ratti and S. venezuelensis are the result of two independent evolutionary transitions to parasitism of rats, which therefore presents an ideal opportunity to begin to investigate the basis of host specificity in Strongyloides spp.
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Strongyloides ratti and S. venezuelensis – rodent models of Strongyloides infection
Parasitology, 2016Co-Authors: Mark Viney, Taisei KikuchiAbstract:Strongyloides spp. are common parasites of vertebrates and two species, S. ratti and S. venezuelensis, parasitize rats; there are no known species that naturally infect mice. Strongyloides ratti and S. venezuelensis overlap in their geographical range and in these regions co-infections appear to be common. These species have been widely used as tractable laboratory systems in rats as well as mice. The core biology of these two species is similar, but there are clear differences in aspects of their within-host biology as well as in their free-living generation. Phylogenetic evidence suggests that S. ratti and S. venezuelensis are the result of two independent evolutionary transitions to parasitism of rats, which therefore presents an ideal opportunity to begin to investigate the basis of host specificity in Strongyloides spp.
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Transgenesis in the parasitic nematode Strongyloides ratti
Molecular and biochemical parasitology, 2011Co-Authors: Hongguang Shao, Mark Viney, Ariel B. Junio, Thomas J. Nolan, Holman C. Massey, Edward J. Pearce, James B. LokAbstract:Strongyloides and related genera are advantageous subjects for transgenesis in parasitic nematodes, primarily by gonadal microinjection as has been used with Caenorhabditis elegans. Transgenesis has been achieved in Strongyloides stercoralis and in ParaStrongyloides trichosuri, but both of these lack well-adapted, conventional laboratory hosts in which to derive transgenic lines. By contrast, Strongyloides ratti develops in laboratory rats with high efficiency and offers the added advantages of robust genomic and transcriptomic databases and substantial volumes of genetic, developmental and immunological data. Therefore, we evaluated methodology for transgenesis in S. stercoralis as a means of transforming S. ratti. S. stercoralis-based GFP reporter constructs were expressed in a proportion of F1 transgenic S. ratti following gonadal microinjection into parental free-living females. Frequencies of transgene expression in S. ratti, ranged from 3.7% for pAJ09 to 6.8% for pAJ20; respective frequencies for these constructs in S. stercoralis were 5.6% and 33.5%. Anatomical patterns of transgene expression were virtually identical in S. ratti and S. stercoralis. This is the first report of transgenesis in S. ratti, an important model organism for biological investigations of parasitic nematodes. Availability of the rat as a well-adapted laboratory host will facilitate derivation of transgenic lines of this parasite.
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Response of the Strongyloides ratti transcriptome to host immunological environment
International journal for parasitology, 2010Co-Authors: Helen O'meara, Mark Viney, Rebecca Barber, Luciane V. Mello, Ajanthah Sangaralingam, Steve PatersonAbstract:The immunological environment experienced by parasitic nematodes varies greatly between hosts and is particularly influenced by whether or not a host has been previously infected. How a parasitic nematode responds to these different environments is poorly understood, but may allow a parasite to ameliorate the adverse effects of host immunity on parasite fitness. Here we use a microarray approach to identify genes in the parasitic nematode Strongyloides ratti that exhibit differential transcription between different rat host immunological environments, and between replicate lines of S. ratti selected for either early or late reproduction. We hypothesise that such genes may be used by this species to cope with and respond to its host environment. Our results showed that, despite large phenotypic differences between S. ratti adults from different immunological environments, the S. ratti transcriptome exhibited a relatively stable pattern of expression. Thus, differential expression amongst treatments was limited to a small proportion of transcripts and generally involved only modest fold changes. These transcripts included a group of collagen genes up-regulated in parasites early in an infection, and in immunised host environments, which may be related to protection against the damage caused to a parasite by host immune responses. We found that later in an infection, a number of genes associated with muscle function and repair were up-regulated in immunised host environments; these may help parasites maintain their position in the host intestine. Differences in transcription between selection lines of S. ratti were only observed in immunised hosts and included genes associated with the response to the host’s immunological environment.
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A genetic map of the animal-parasitic nematode Strongyloides ratti
Molecular and biochemical parasitology, 2009Co-Authors: Linda Nemetschke, Mark Viney, Alexander G. Eberhardt, Adrian StreitAbstract:Classical genetic approaches are rarely used with metazoan endo-parasites, largely because the adult stages are usually hidden within hosts, making controlled crosses difficult. The nematode Strongyloides ratti is a parasite of the small intestine of rats, and is a relative of the parasite of humans S. stercoralis. The life-cycle of Strongyloides spp. has a facultative free-living adult generation. Here we describe procedures for genetic mapping, and a genetic map, for S. ratti. This is, as far as we are aware, the first genetic map of an animal parasitic nematode. This significantly improves the usefulness of S. ratti as experimentally tractable system for parasitological investigations and for comparative studies with the model nematode Caenorhabditis elegans.
Isao Tada - One of the best experts on this subject based on the ideXlab platform.
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Strongyloides ratti implication of mast cell mediated expulsion through fceri independent mechanisms
Parasite, 2009Co-Authors: Masataka Koga, Kanji Watanabe, Shinjiro Hamano, Kenji Kishihara, K. Nomoto, Isao TadaAbstract:Afin de determiner si la degranulation des mastocytes, apres agregation du recepteur de haute affinite des IgE (FceRI), est responsable de l'expulsion des nematodes intestinaux Strongyloides ratti, des souris CD45-/- (deficiente pour l'exon 6 de CD45) sont infectees par le nematode. Chez les souris CD45-/-, l'excretion des œufs persiste plus de 30 jours apres l'inoculation de larves de S. ratti alors que chez les souris de type sauvage (CD45+/+), il n'y a plus d'excretion 20 jours post-infection. Il y a 75 % en moins de mastocytes au niveau de la muqueuse intestinale chez les souris CD45-/- par rapport aux souris CD45+/+. Le transfert de lymphocytes T de souris sauvage (CD45+/+) aux souris CD45-/- reduit la duree de secretion a des niveaux comparables a ceux observes dans le type sauvage avec une augmentation concomitante de mastocytes au niveau de la muqueuse intestinale. Ces resultats montrent que CD45 n'est pas impliquee dans la fonction eifectrice des mastocytes de la muqueuse intestinale lors d'une infection par S. ratti. Etant donne que la degranulation des mastocytes apres agregation du recepteur FceRI est impossible chez les souris CD45-/-, nous en concluons que la degranulation des mastocytes, dependante du recepteur FceRI, n'est pas necessaire pour l'expulsion de S. ratti.
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Strongyloides ratti: thermokinesis of glycolytic enzyme- and lectin-treated third-stage infective larvae in vitro
Parasitology Research, 2005Co-Authors: Hiroe Tobata-kudo, Hideaki Kudo, Isao TadaAbstract:The infective third-stage larvae (L3s) of a parasitic nematode of rodents, Strongyloides ratti , showed three types of thermokinesis on a temperature gradient using an in vitro agarose tracking assay method. These depended both on the pattern of gradient temperature and the prior culture temperature. Most L3s (≥ 80%) isolated from rat feces cultured at 25°C and placed on a gradient at temperatures between 30°C and 37°C showed no directional response, at 22–29°C more than 50% of the L3s showed positive thermokinesis, at 21°C L3s showed positive, negative and no directional responses in the same ratio, while at 18–20°C, L3s showed negative thermokinesis (approx. 40%) or no directional response (approx. 60%) as in our previous study. The present study describes the effects of glycolytic enzyme- and lectin-treated positive thermokinesis of L3s. α-Glucosidase or concanavalin A significantly exhibited inhibitory effects on thermokinesis.
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Strongyloides ratti: chemokinesis of glycolytic enzyme- and lectin-treated third-stage infective larvae in vitro.
Parasitology International, 2005Co-Authors: Hiroe Tobata-kudo, Hideaki Kudo, Isao TadaAbstract:Abstract The infective third-stage larvae (L3s) of Strongyloides ratti , a parasitic nematode in rodents, showed two types of chemokinesis on a gradient of sodium chloride (NaCl) in an in vitro agarose tracking assay. The types were a consistent directional avoidance behavior under unfavorable environmental conditions and a reduced avoidance behavior under favorable conditions. We examined the effects of treatments with glycolytic enzymes and lectins by analyzing the avoidance behavior. l -Fucose dehydrogenase, hyaluronidase, β-glucosidase, α-mannosidase, β-galactosidase, concanavalin A, wheat germ agglutinin and soybean agglutinin exhibited inhibitory or enhancive effects on chemokinesis. We also confirmed the sites of the amphids of L3s aside from the mouth at the anterior end by scanning electron microscopy, and that concanavalin A-binding sites existed in the vicinity of the amphids using lectin-histochemistry. The carbohydrate moieties in the amphids of S. ratti L3s may play an important role as chemosensors in perceiving environmental cues.
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Strongyloides ratti: the role of interleukin-5 in protection against tissue migrating larvae and intestinal adult worms.
Journal of helminthology, 2003Co-Authors: Kanji Watanabe, Isao Tada, O. Sasaki, Shinjiro Hamano, Kenji Kishihara, K. Nomoto, Yoshiki AokiAbstract:To determine the role of interleukin-5 (IL-5) and eosinophils in protection against Strongyloides ratti , mice treated with anti-IL-5 monoclonal antibody (mAb) were infected with S. ratti larvae. Strongyloides ratti egg numbers in faeces (EPG) in mAb treated mice were higher than those in control mice on days 6 and 7 after inoculation. The numbers of migrating worms in mAb treated mice 36 h after inoculation were higher than those observed in control mice. Intestinal worm numbers in mAb treated mice 5 days after inoculation were higher than those in control mice. These results show that eosinophils effectively protected the host against S. ratti infection by mainly the larval stage in primary infections. The involvement of eosinophils in protection against secondary infection was also examined. Before secondary infection, mice were treated with anti-IL-5 mAb and infected with S. ratti . Patent infections were not observed in either mAb treated or control Ab treated mice. The numbers of migrating worms in the head and lungs of mAb treated mice increased to 60% of that in primary infected mice. Intestinal worms were not found in mAb treated mice or in contcrol mice after oral implantation of adult worms. Eosinophils were therefore mainly involved in protection against tissue migrating worms in secondary infections.
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Chemokinetic behavior of the infective third-stage larvae of Strongyloides ratti on a sodium chloride gradient.
Parasitology international, 2000Co-Authors: Hiroe Tobata-kudo, Hiroo Higo, Masataka Koga, Isao TadaAbstract:The movements of the infective third-stage larvae (L3) of a rodent parasitic nematode Strongyloides ratti were examined on a sodium chloride (NaCl) gradient set up on agarose plates. The movements of larvae were followed by observing their tracks on the surface of the agarose. The direction of movement depended on the NaCl concentration at the point of their initial placement on the gradient. Larvae placed at between 230 and 370 mM NaCl tended to migrate towards areas of lower concentration. On the other hand, when placed at concentrations less than 20 mM NaCl, larvae tended to migrate initially towards higher concentrations but did not linger in areas where the concentration was over approximately 80 mM NaCl. It seems that S. ratti L3, tested in vitro, prefer regions with a concentration of NaCl below 80 mM NaCl. Two typical chemokinetic behaviors are seen; a unidirectional avoidance movement when initially placed in unfavorable environmental conditions and a random dispersal movement when placed within an area of favorable conditions. Track patterns were straight in the avoidance movement but included multiple changes of direction and loops in the dispersal movement. This study introduces an assay system suitable for studying chemokinetic behavior of larvae of Strongyloides ratti.
Takaya Sakura - One of the best experts on this subject based on the ideXlab platform.
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Assessment of skin penetration of third-stage larvae of Strongyloides ratti
Parasitology Research, 2010Co-Authors: Takaya SakuraAbstract:Strongyloides stercoralis infection is caused by skin penetration of third-stage larvae (L3s). We studied skin penetration of L3s of Strongyloides ratti using an in vitro assay that has been used previously to study Angiostrongylus cantonensis , an agarose membrane with a temperature gradient, and scanning electron microscopy. Our results revealed that skin penetration of L3s depended on host skin temperature. When the target temperature of the outer liquid was 37°C, more than 80% of L3s penetrated the skin, but penetration was only 60% when the target temperature was 20°C. Thirdstage larvae moved rapidly on the agarose membrane toward optimum temperature area for this parasite, which indicates that L3 has a sensor that is sensitive to temperature changes. Penetration rate for hosts such as cat (36%), dog (32%), and bird (13%) were significantly lower than that for rat (82%). Although we could not establish the reason, L3s seemed to have an ability to differentiate these hosts at the time of penetration. By using scanning electron microscopy, penetration of L3s could be observed within 10 min. We demonstrated thermotaxis of L3 of S. ratti , and this peculiar characteristic seemed to have a close relationship with the process of searching for the host.
Hiroe Tobata-kudo - One of the best experts on this subject based on the ideXlab platform.
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Strongyloides ratti: thermokinesis of glycolytic enzyme- and lectin-treated third-stage infective larvae in vitro
Parasitology Research, 2005Co-Authors: Hiroe Tobata-kudo, Hideaki Kudo, Isao TadaAbstract:The infective third-stage larvae (L3s) of a parasitic nematode of rodents, Strongyloides ratti , showed three types of thermokinesis on a temperature gradient using an in vitro agarose tracking assay method. These depended both on the pattern of gradient temperature and the prior culture temperature. Most L3s (≥ 80%) isolated from rat feces cultured at 25°C and placed on a gradient at temperatures between 30°C and 37°C showed no directional response, at 22–29°C more than 50% of the L3s showed positive thermokinesis, at 21°C L3s showed positive, negative and no directional responses in the same ratio, while at 18–20°C, L3s showed negative thermokinesis (approx. 40%) or no directional response (approx. 60%) as in our previous study. The present study describes the effects of glycolytic enzyme- and lectin-treated positive thermokinesis of L3s. α-Glucosidase or concanavalin A significantly exhibited inhibitory effects on thermokinesis.
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Strongyloides ratti: chemokinesis of glycolytic enzyme- and lectin-treated third-stage infective larvae in vitro.
Parasitology International, 2005Co-Authors: Hiroe Tobata-kudo, Hideaki Kudo, Isao TadaAbstract:Abstract The infective third-stage larvae (L3s) of Strongyloides ratti , a parasitic nematode in rodents, showed two types of chemokinesis on a gradient of sodium chloride (NaCl) in an in vitro agarose tracking assay. The types were a consistent directional avoidance behavior under unfavorable environmental conditions and a reduced avoidance behavior under favorable conditions. We examined the effects of treatments with glycolytic enzymes and lectins by analyzing the avoidance behavior. l -Fucose dehydrogenase, hyaluronidase, β-glucosidase, α-mannosidase, β-galactosidase, concanavalin A, wheat germ agglutinin and soybean agglutinin exhibited inhibitory or enhancive effects on chemokinesis. We also confirmed the sites of the amphids of L3s aside from the mouth at the anterior end by scanning electron microscopy, and that concanavalin A-binding sites existed in the vicinity of the amphids using lectin-histochemistry. The carbohydrate moieties in the amphids of S. ratti L3s may play an important role as chemosensors in perceiving environmental cues.
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Chemokinetic behavior of the infective third-stage larvae of Strongyloides ratti on a sodium chloride gradient.
Parasitology international, 2000Co-Authors: Hiroe Tobata-kudo, Hiroo Higo, Masataka Koga, Isao TadaAbstract:The movements of the infective third-stage larvae (L3) of a rodent parasitic nematode Strongyloides ratti were examined on a sodium chloride (NaCl) gradient set up on agarose plates. The movements of larvae were followed by observing their tracks on the surface of the agarose. The direction of movement depended on the NaCl concentration at the point of their initial placement on the gradient. Larvae placed at between 230 and 370 mM NaCl tended to migrate towards areas of lower concentration. On the other hand, when placed at concentrations less than 20 mM NaCl, larvae tended to migrate initially towards higher concentrations but did not linger in areas where the concentration was over approximately 80 mM NaCl. It seems that S. ratti L3, tested in vitro, prefer regions with a concentration of NaCl below 80 mM NaCl. Two typical chemokinetic behaviors are seen; a unidirectional avoidance movement when initially placed in unfavorable environmental conditions and a random dispersal movement when placed within an area of favorable conditions. Track patterns were straight in the avoidance movement but included multiple changes of direction and loops in the dispersal movement. This study introduces an assay system suitable for studying chemokinetic behavior of larvae of Strongyloides ratti.
Steve Paterson - One of the best experts on this subject based on the ideXlab platform.
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Response of the Strongyloides ratti transcriptome to host immunological environment
International journal for parasitology, 2010Co-Authors: Helen O'meara, Mark Viney, Rebecca Barber, Luciane V. Mello, Ajanthah Sangaralingam, Steve PatersonAbstract:The immunological environment experienced by parasitic nematodes varies greatly between hosts and is particularly influenced by whether or not a host has been previously infected. How a parasitic nematode responds to these different environments is poorly understood, but may allow a parasite to ameliorate the adverse effects of host immunity on parasite fitness. Here we use a microarray approach to identify genes in the parasitic nematode Strongyloides ratti that exhibit differential transcription between different rat host immunological environments, and between replicate lines of S. ratti selected for either early or late reproduction. We hypothesise that such genes may be used by this species to cope with and respond to its host environment. Our results showed that, despite large phenotypic differences between S. ratti adults from different immunological environments, the S. ratti transcriptome exhibited a relatively stable pattern of expression. Thus, differential expression amongst treatments was limited to a small proportion of transcripts and generally involved only modest fold changes. These transcripts included a group of collagen genes up-regulated in parasites early in an infection, and in immunised host environments, which may be related to protection against the damage caused to a parasite by host immune responses. We found that later in an infection, a number of genes associated with muscle function and repair were up-regulated in immunised host environments; these may help parasites maintain their position in the host intestine. Differences in transcription between selection lines of S. ratti were only observed in immunised hosts and included genes associated with the response to the host’s immunological environment.
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Immunological responses elicited by different infection regimes with Strongyloides ratti.
PloS one, 2008Co-Authors: Steve Paterson, Cp Wilkes, Colin Bleay, Mark VineyAbstract:Nematode infections are a ubiquitous feature of vertebrate life. In nature, such nematode infections are acquired by continued exposure to infective stages over a prolonged period of time. By contrast, experimental laboratory infections are typically induced by the administration of a single (and often large) dose of infective stages. Previous work has shown that the size of an infection dose can have significant effects on anti-nematode immune responses. Here we investigated the effect of different infection regimes of Strongyloides ratti, comparing single and repeated dose infections, on the host immune response that was elicited. We considered and compared infections of the same size, but administered in different ways. We considered infection size in two ways: the maximum dose of worms administered and the cumulative worm exposure time. We found that both infection regimes resulted in Th2-type immune response, characterised by IL4 and IL13 produced by S. ratti stimulated mesenteric lymph node cells, anti-S. ratti IgG1 and intestinal rat mast cell protease II (RMCPII) production. We observed some small quantitative immunological differences between different infection regimes, in which the concentration of IL4, IL13, anti-S. ratti IgG1 and IgG2a and RMCPII were affected. However, these differences were quantitatively relatively modest compared with the temporal dynamics of the anti-S. ratti immune response as a whole.
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Density-dependent immune responses against the gastrointestinal nematode Strongyloides ratti
International journal for parasitology, 2007Co-Authors: Colin Bleay, Cp Wilkes, Steve Paterson, Mark VineyAbstract:Negative density-dependent effects on the fitness of parasite populations are an important force in their population dynamics. For the parasitic nematode Strongyloides ratti, density-dependent fitness effects require the rat host immune response. By analysis of both measurements of components of parasite fitness and of the host immune response to different doses of S. ratti infection, we have identified specific parts of the host immune response underlying the negative density-dependent effects on the fitness of S. ratti. The host immune response changes both qualitatively from an inflammatory Th1- to a Th2-type immune profile and the Th2-type response increases quantitatively, as the density of S. ratti infection increases. Parasite survivorship was significantly negatively related to the concentration of parasite-specific IgG1 and IgA, whereas parasite fecundity was significantly negatively related to the concentration of IgA only.
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Experimental evolution of parasite life-history traits in Strongyloides ratti (Nematoda)
Proceedings. Biological sciences, 2007Co-Authors: Steve Paterson, Rebecca BarberAbstract:Evolutionary ecology predicts that parasite life-history traits, including a parasite's survivorship and fecundity within a host, will evolve in response to selection and that their evolution will be constrained by trade-offs between traits. Here, we test these predictions using a nematode parasite of rats, Strongyloides ratti, as a model. We performed a selection experiment by passage of parasite progeny from either early in an infection ('fast' lines) or late in an infection ('slow' lines). We found that parasite fecundity responded to selection but that parasite survivorship did not. We found a trade-off mediated via conspecific density-dependent constraints; namely, that fast lines exhibit higher density-independent fecundity than slow lines, but fast lines suffered greater reduction in fecundity in the presence of density-dependent constraints than slow lines. We also found that slow lines both stimulate a higher level of IgG1, which is a marker for a Th2-type immune response, and show less of a reduction in fecundity in response to IgG1 levels than for fast lines. Our results confirm the general prediction that parasite life-history traits can evolve in response to selection and indicate that such evolutionary responses may have significant implications for the epidemiology of infectious disease.
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The immune response during a Strongyloides ratti infection of rats.
Parasite immunology, 2007Co-Authors: Cp Wilkes, Colin Bleay, Steve Paterson, Mark VineyAbstract:A range of immune parameters were measured during a primary infection of Strongyloides ratti in its natural rat host. The immune parameters measured were IL-4 and IFN-γ from both the spleen and MLN cells; parasite specific IgG1, IgG2a and IgG2b in serum and in intestinal tissue; parasite specific IgG and total IgE in serum; parasite specific and total IgA in intestinal tissue and rat mast cell protease II in intestinal tissue. Parasite specific IgG1, IgG2a and total IgE in serum and parasite specific IgA and rat mast cell protease II in intestinal tissue all occurred at significantly greater concentrations in infected animals, compared with non-infected animals. Similarly, the production of IL-4 by MLN cells stimulated with parasitic female antigen or ConA occurred at significantly greater concentrations in infected animals, compared with non-infected animals. In all, this suggests that there is a Th2-type immune response during a primary S. ratti infection. These data also show the temporal changes in these components of the host immune response during a primary S. ratti infection.
