Lymphocyte proliferation rate was determined by ³H-thymidine incorporation assay after stimulation of peripheral blood mononuclear cells (PBMC) from BLV and BIV-infected cattle with mitogens: concanavalin A, phytohaemagglutitin, and pokeweed mitogen. BLV infection were associated with significant decrease in lymphocyte proliferation, as compared to uninfected animals. Co-infection with BIV strongly increased antimitotic influence of BLV, mainly in PL-animals. These results demonstrated that a function impairement of lymphocytes can be observed in the course of BLV and/or BLV/BIV infection.
The purpose of this study was searching for sequences similar to bovine leukaemia virus genome in the genome of BLV-free cattle. The study was performed using PCR method and hybridisation. Products of amplification with starters specific for BLV genome was discovered. The presence of these sequences was confirmed by hybridisation with molecular probe complementary to BLV genome. It cannot be ruled out that these are endogenous sequences similar to bovine leukaemia virus in the genome of BLV-free cattle.