Elisabeth A Innes

..However, a recurring theme in the recent review by Hemphill et al. is not the similarities but the striking differences between the two parasites...

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..In this paper we will discuss some of the history, challenges and progress in the development of veterinary vaccines against T. gondii...

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..A live vaccine, Toxovax is the only commercially available vaccine worldwide to protect against congenital toxoplasmosis...

..This paper discusses current vaccination strategies to help combat infections with Eimeria, Toxoplasma and Neospora and recent research looking towards developing new vaccine targets and approaches...

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..caninum. This is likely to involve a fine balancing act with the immune system that will allow intervention in a manner that will tip the host-parasite balance in favour of the host without compromising the pregnancy...

..gondii with a tendency for samples from certain genetic lines of Charollais sheep more likely to be positive than samples from other lines, suggesting that some sheep have a particular genetic susceptibility to T. gondii...

..These studies show that intra-nasal delivery has the potential to be an effective route for mucosal immunisation in sheep...

..At day 42 pi, specific cell-mediated immune responses were not apparent; however, N. caninum-specific fetal IgG and IgM antibodies were detected...

..caninum during pregnancy killed all the fetuses while inoculation before pregnancy did not cause any mortality but did provide a degree of protection against subsequent challenge with Neospora during pregnancy...

..So, is vaccination a feasible option to control the disease? This article discusses some of these issues and reports on the progress towards a vaccine for neosporosis...

..Vaccination prior to pregnancy with Toxovax did protect against foetal death following oral challenge at 90 days with 2000 T. gondii oocysts which caused 100% foetal death in a control challenge group...

..This study shows that the generation of robust peripheral and local maternal CMI responses (lymphoproliferation, IFN-γ) may inhibit the vertical transmission of the parasite...

..The results of this study indicate that red foxes of the UK have more exposure to T. gondii than to N. caninum in their environment...

..In conclusion, N. caninum infection is present among Paraguayan beef and dairy cattle, and it may be an important cause of bovine abortion in Paraguay...

..9 per cent of aborted fetuses had antibody to the parasite shows that vertical transmission from dam to fetus is relatively common and may be an important cause of fetal loss in cattle in Scotland...

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..These results suggest that the immune response generated in the dams in group 2 prior to pregnancy had protected against vertical transmission of the parasite following challenge at mid-gestation...

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..Of the two inoculation routes, the intravenous induced the more acute placental lesions and greater mortality...

..This suggests that a change in the maternal immune response plays a crucial role in limiting the initial infection during the last term of pregnancy...

..gondii infection. Only 24.7% of farmers used the vaccine and the vaccine did not significantly affect the within flock seroprevalence for T. gondii. The implications for food safety and human infection are discussed...

..It is possible that a pro-inflammatory Th-1 response early in gestation protects the dam by eliminating the parasite; however, it may lead to destruction of the placental tissues themselves and thus be incompatible with fetal survival...

..If this were so it raises the question of whether the vaccine could be used to make meat safer for human consumption...

..These results would suggest that it is possible to attenuate the virulence of N. caninum tachyzoites in mice through prolonged in vitro passage...

..All mice in group 2 were protected following challenge on day 48 p.i. whereas naïve control mice succumbed to the challenge. No mice from group 1 (virulent) survived beyond day 24 p.i. so they were not included in the challenge...

..However, more severe pathology developed in mice initially inoculated with virulent parasites following a secondary challenge, compared to mice initially inoculated with attenuated parasites...

..The genetic and biological diversity observed in this study may have important implications for our understanding of the pathology and epidemiology of neosporosis...

..CD4+ T-cells, interferon gamma and macrophages have all been found to significantly inhibit multiplication of N. caninum tachyzoites. The nature of a protective immune response and its modulation in the pregnant animal is discussed...

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..Finally, conclusions are drawn with regard to the most promising methods and directions of future research...