Bovine Leukemia virus (BLV) is a retrovirus that is closely related to human T cell leukemia virus (HTLV) with a major distinction of infecting B cells primarily. Persistent lymphocytosis (PL) is a subclinical condition characterized by the polyclonal expansion of B cells, and the progression to PL is under host genetic control. However, the influence of retroviral infections on the immunological status are not fully established in cattle. Towards this end, we have studied the levels of cytokine mRNA expression of CD4+ cells and peripheral blood mononuclear cells (PBMC) by semi-quantitative RT-PCR in BLV infected non-PL and PL animals, along with uninfected controls. Our analysis indicates a significant reduction in IL-2 and IL-4 mRNA expression levels in enriched CD4+ T cells and in PBMCs of PL animals. Additionally, a significant reduction of TNF-α was also observed in fresh PBMCs. After activation with Con-A, no differences were observed. Interestingly, the frequency of fresh CD4+ T cells expressing cytokine mRNA was not different among groups as detected by a direct RT-PCR methodology. These results suggest an alteration of T cell responses in PL animals.
|Publication status||Published - 20 Mar 1998|