Cellular immunity against Theileria parva and its influence on parasite diversity.
Theileria parva, a tick-borne parasite of African cattle, causes a fatal disease known as East Coast fever. Cattle that recover from the disease develop strong parasite-specific MHC-class I-restricted cytotoxic T-lymphocyte responses. Protection can be transferred between immune and naïve calves in the CD8+ T cell fraction emanating from a responding lymph node. In vitro studies suggest that this response requires input from activated CD4+ T cells. The T parva life cycle involves developmental stages in mammalian and tick hosts and can lead to a number of different endemic scenarios for the disease. These range from a stable situation with high prevalence of herd infection, but low fatality rates, to a low prevalence/high fatality scenario. The impact on endemic stability is an important consideration for the design of vaccine implementation strategies. For subunit vaccines targeted at T parva schizonts, the principal issue in this regard is whether development of the piroplasm stage is blocked by immunity.
McKeever
D J
DJ
Moredun Research Institute, Penicuik Midlothian, Department of Veterinary Clinical Studies, University of Edinburgh, Scotland, UK.
D000818:Animals; D002417:Cattle; D006790:Host-Parasite Interactions; D007111:Immunity, Cellular; D007113:Immunity, Innate; D008018:Life Cycle Stages; D016797:Theileria parva / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D013801:Theileriasis / Q000276:immunology*