Quantitative Analysis of Cytokine mRNA Expression and Protozoan DNA Load in Theileria parva-Infected Cattle(Immunology)

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Theileria parva (T. parva) causes a highly serious bovine disease called East Coast fever (ECF), which is characterlzed by pyrexia, dyspnea and cachexia and is of great economic importance in African countries. We hypothesize that the clinical symptoms of ECF could be explained by a cytokine dysregulation. In this study, we investigated the relationship between T. parva DNA load and expression levels of cytokine mRNAs in leukocytes from experimentally infected calves by quantitative PCR. The p104 gene, which encodes the T. parva 104kDa microneme-rhoptry protein, was detected in cattle blood from day 10 after T. parva-infected tick infestation, and the protozoan DNA load was increased together with severity of disease. The mRNA expressions of pro-inflammatory cytokines, such as interleukin (IL)-1β and IL-6, were up-regulated with protozoan DNA load increasing. In addition, the level of a type-2 cytokine (IL-10) transcript was also increased during the acute phase. In contrast, the down-regulation or no detectable levels of the expression of type-1 cytokines, such as IL-2 and interferon (IFN)-γ were observed in T. parva-infected animals. Thus, our observations indicated that high protozoan load and resulting intense inflammatory responses might be involved ill the severity of clinical signs observed in T. parva-infection.
社団法人日本獣医学会の論文
2009-01-25