2004

DOI: 10.1007/s00436-004-1194-5

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The role of B- and T-cell immunity in toltrazuril-treated C57BL/6 WT, �MT and nude mice experimentally infected with Neospora caninum

¹

,

Andreas Waldvogel

²

,

³

et al.

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Cited by 5 publications

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“…The apparent absence of parasite DNA in some of the brain samples could be due to a low parasite burden rather than to a total absence of parasites. A similar lack of parasite DNA, as determined by PCR, in brain samples of N. caninum ‐infected calves or mice has previously been described (7,48). Moreover the high serum levels of N. caninum ‐specific IgG detected in mice 6 months after the i.g.…”

Section: Discussionsupporting

confidence: 68%

Analysis of the immune response to Neospora caninum in a model of intragastric infection in mice

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²

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³

et al. 2006

Parasite Immunology

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To study experimental Neospora caninum infection initiated at the gastrointestinal tract, Toll-like Receptor 4- and functional IL-12Rbeta2 chain-deficient C57BL/10 ScCr mice were challenged intragastrically with 5 x 10(6) N. caninum tachyzoites. All parasite-inoculated mice eventually died with disseminated infection. In contrast, immunocompetent BALB/c mice challenged with 1 x 10(7) N. caninum tachyzoites by the intragastric (i.g.) or the intraperitoneal (i.p.) route remained alive for at least 6 months. Expansion of splenic B- and T-cells, the latter displaying both activated and regulatory phenotypes, and increased levels of IFN-gamma and IL-10 mRNA were detected in both groups of infected BALB/c mice compared with non-infected controls, whereas in the Peyer's patches only IFN-gamma mRNA levels were found to be increased. Parasite-specific IgG1, IgG2a and IgA antibody levels were elevated in the sera of all infected mice, whereas increased N. caninum-specific IgA levels were detected in intestinal lavage fluids of i.g. challenged mice only. These results show that N. caninum infection can be successfully established in mice by i.g. administration of tachyzoites. They also show that the immune response elicited in i.g. or i.p. infected BALB/c mice, although conferring some degree of protection, was not sufficient for complete parasite clearance.

“…The apparent absence of parasite DNA in some of the brain samples could be due to a low parasite burden rather than to a total absence of parasites. A similar lack of parasite DNA, as determined by PCR, in brain samples of N. caninum ‐infected calves or mice has previously been described (7,48). Moreover the high serum levels of N. caninum ‐specific IgG detected in mice 6 months after the i.g.…”

Section: Discussionsupporting

confidence: 68%

Analysis of the immune response to Neospora caninum in a model of intragastric infection in mice

¹

,

²

,

³

et al. 2006

Parasite Immunology

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To study experimental Neospora caninum infection initiated at the gastrointestinal tract, Toll-like Receptor 4- and functional IL-12Rbeta2 chain-deficient C57BL/10 ScCr mice were challenged intragastrically with 5 x 10(6) N. caninum tachyzoites. All parasite-inoculated mice eventually died with disseminated infection. In contrast, immunocompetent BALB/c mice challenged with 1 x 10(7) N. caninum tachyzoites by the intragastric (i.g.) or the intraperitoneal (i.p.) route remained alive for at least 6 months. Expansion of splenic B- and T-cells, the latter displaying both activated and regulatory phenotypes, and increased levels of IFN-gamma and IL-10 mRNA were detected in both groups of infected BALB/c mice compared with non-infected controls, whereas in the Peyer's patches only IFN-gamma mRNA levels were found to be increased. Parasite-specific IgG1, IgG2a and IgA antibody levels were elevated in the sera of all infected mice, whereas increased N. caninum-specific IgA levels were detected in intestinal lavage fluids of i.g. challenged mice only. These results show that N. caninum infection can be successfully established in mice by i.g. administration of tachyzoites. They also show that the immune response elicited in i.g. or i.p. infected BALB/c mice, although conferring some degree of protection, was not sufficient for complete parasite clearance.

“…Thus, when applied for a few days under these experimental conditions, toltrazuril exhibits only parasitostatic activity. In experimentally infected mice a 6-day toltrazuril treatment also had a more parasitostatic rather than a parasiticidal effect (Ammann et al 2004). A clear parasiticidal effect of toltrazuril, defined in our assay by the failure to detect NcGRA2 mRNA, was first observed after a continuous long-term treatment of 14 days.…”

Section: Discussionmentioning

confidence: 99%

“…In the murine model of experimental N. caninum infection, toltrazuril treatment prevented severe clinical signs and the formation of cerebral lesions (Gottstein et al 2001; Darius et al 2004 a ). However, Ammann et al (2004) clearly demonstrated that an efficient metaphylaxis requires at least a T-cell-mediated immunological support in mice. We now used NcGra2 as a target gene to demonstrate viability or non-viability of N. caninum in affected host cells following treatment with the anti-parasitic compound toltrazuril.…”

Section: Introductionmentioning

confidence: 99%

NcGRA2as a molecular target to assess the parasiticidal activity of toltrazuril againstNeospora caninum

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²

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³

et al. 2008

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The treatment of Neospora caninum infection in the bovine host is still at an experimental stage. In contrast to the in vivo situation, a wide range of compounds have been intensively investigated in cell-culture-based assays. Tools to demonstrate efficacy of treatment have remained conventional including morphological and cell biological criteria. In this work, we present a molecular assay that allows the distinction between live and dead parasites. Live parasites can be detected by measuring the mRNA level of specific genes, making use of the specific mRNA available in live cells. The NcGra2 gene of N. caninum, which is known to be expressed in both tachyzoites and bradyzoites, was used to establish a quantitative realtime RT-PCR, for monitoring parasite viability. Validation of the system in vitro was achieved using Neospora-infected cells that had been treated for 2-20 days with 30 mg/ml toltrazuril. NcGRA2-RT-real time PCR demonstrated that a 10-day toltrazuril-treatment exerted parasitostatic activity, as assessed by the presence of NcGRA2-transcripts, whereas after a 14-day treatment period no NcGRA2-transcripts were detected, showing that the parasites were no longer viable. Concurrently, extended culture for a period of 4 weeks in the absence of the drug following the 14-day toltrazuril treatment did not lead to further parasite proliferation, confirming the parasiticidal effect of the treatment. This assay has the potential to be widely used in the development of novel drugs against N. caninum, with a view to distinguishing between parasiticidal and parasitostatic efficacy of given compounds.

“…The efficacy of PZQ has been shown to be dependent on host immune responses for example in a study that showed the activity of PZQ to be dependent on T cell-mediated immunity [56] and many experimental studies in immunosuppressed S. mansoni infected mice that were T-cell deprived or B-cell depleted [57][58][59]. Another study showed that following PZQ exposure in vivo, sexually mature worms had damaged tegument surfaces that resulted in the exposure of parasite antigens to the host humoral immune system [60] and also triggered the recruitment of innate immune cells most likely caused parasite elimination [61].…”

Section: Discussionmentioning

confidence: 99%

Immunomodulating Potential of Ekebergia capensis in Murine Schistosoma mansoni Juvenile and Adult Infection

Musili,

Lusweti,

Kinyatta

et al. 2024

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Schistosomiasis is a neglected tropical disease occurring in sub-Saharan Africa and affecting almost 250 million people. The drug of choice for treatment for Schistosomiasis has been Praziquantel which has been used for many years and there is a need to develop new drugs. The immunomodulatory potential of Ekebergia capensis extract on both juvenile and adult Schistosoma mansoni infection in vivo was evaluated in this study. Swiss albino mice were infected individually with 90 S. mansoni cercariae and randomized into groups of five each for i) plant extract treated groups ii) positive control groups treated with conventional drugs PZQ or artemether iii) infected but untreated (negative control) groups. The mice were treated orally with aqueous extracts of E. capensis at doses of 200 and 400 mg/kg at 2 weeks (juvenile worms) and 7 weeks (adult worms) post-infection. Immune immune-enhancing potential of the medicinal plant was determined by analyzing the levels of cytokines in serum samples that were collected before and after treatment. A BD-Cytometric Bead Array (CBA) mouse Th1/Th2/Th17 kit was used to quantitate the levels of cytokines using a flow cytometer (FACS Calibur) and analysis of the data was done using FCAP software. Results indicated that the medicinal plant extract had an immunomodulatory effect. There was a significant increase (P<0.05) in Th1 cytokines (IL-2, IFN- γ and TNF-α), a decrease in Th2 cytokines (IL-4, IL-6 and IL-10) and an increase in Th17 (IL-17). These findings confirm the potential use of medicinal plants in the management of schistosomiasis.

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