Neospora Research at Moredun
Host pathogen interactions
Study of host-parasite relationships in pregnant cattle showed that:
- Infection in the first trimester of pregnancy is more likely to result in foetal death compared with infection during mid or late gestation.
- Foetal immune responses mature throughout pregnancy and the foetus is able to mount a specific antibody and cell mediated immune response to the parasite from 4-5 month of gestation onwards.
- Cell mediated immune responses involving CD4+ and CD8+ T cells and interferon gamma (IFNg) are important in protective immunity against N. caninum.
- Maternal cell mediated inflammatory immune responses within infected placental tissues may cause damage to the placenta and compromise pregnancy.
- Infection of cattle with N. caninum tachyzoites, prior to mating, protected cattle against vertical transmission following challenge during pregnancy.
- Long term passage of N. caninum tachyzoites in vitro results in attenuation of virulence in vivo using a mouse model.
- Immunisation with attenuated parasites protected mice against a lethal N. caninum challenge and therefore has potential as a vaccine candidate.
- Diagnostic tests have been developed to detect antibodies, specific for N. caninum, in bovine blood.
- Histo-pathological and immune-histo-pathological procedures have been developed to detect lesions and N. caninum in aborted bovine foetuses, to diagnose the cause of abortion.
- An improved diagnostic nested PCR, that is more sensitive than histo-pathology, has been developed to detect the presence of N. caninum DNA in bovine abortions. This test showed that about 17.5% of bovine abortions within Scotland are infected with N. caninum, bases on 585 samples collected between 2007 and 2009.
- Molecular typing tools have been developed that allow the characterisation of Neospora isolates and the study of transmission routes.
- A wide variety of wildlife reservoir hosts, including ferrets, polecats, foxes, badgers and mink, have been identified although there is no evidence to date that these species may act as definitive hosts by spreading oocysts.
Current Research Interests
- Development of a vaccine that prevents bovine abortion and transmission of the parasite.
- Development of improved diagnostic tests, which can reliably detect carrier animals.
- Identify N. caninum antigens that are recognised by protective immune responses.
- Improve understanding of N. caninum pathogenesis to determine how infection of N. caninum leads to abortion and may lead to immunological tolerance.
- Identify factors involved in parasite reactivation during infection as these may be targets to reduce vertical transmission.
- Evaluate N. caninum transmission dynamics on farms and in wildlife hosts to identify targets that will reduce the spread of the pathogen.
- Assessment of disease impact depending on route of original infection i.e. congenital infection versus horizontal transmission.
- Assessment of the economic impact of the disease.
- Improve N. caninum control strategies to provide better advice for farmers.
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