Cytokine and inducible nitric oxide synthase gene expressions in peripheral blood mononuclear cells and related clinical characteristics in Theileria orientalis sergenti-infected calves.

Eight splenectomized calves were inoculated with Theileria orientalis sergenti (Tos)-infected tick gland homogenate (5 calves) or infected erythrocyte suspension (3 calves). Clinical characteristics were different in calves post-infection. Animals were divided into 3 groups on the basis of susceptibility as high, middle, and low. Increase in mRNA of IFN-gamma, IL-2, and TNF-alpha was observed in peripheral blood mononuclear cells at the peak of infection and was seen to be related with pyrexia and parasitemia. Expression of IL-1, IL-4, and inducible nitric oxide synthase was not observed. Decreased plasma nitrite/nitrate level was observed in the groups. The results of this study indicate that Th1 response is the predominant response in Tos infection, and this response is also related with their clinical characteristics.