Bovine leukemia virus, a distinguished member of the human T-lymphotropic virus family.

Bovine leukemia virus (BLV) has many structural and functional characteristics in common with the human T-lymphotropic viruses (HTLVs). The most striking feature of these retroviruses is the existence of a long open reading frame (LOR) located at the 3' side of the provirus between the right end of the 3' side of env gene and the left end of the long terminal repeat (LTR). It is believed that the LOR protein product is of critical importance in the induction process of the tumor phase of bovine leukemia. Prevention of BLV infection will be attempted by vaccination. To that aim, careful study of BLV envelope glycoprotein epitopes has shown that epitopes F, G, and H play a major role in biological activities of the virus. Their native structure depends upon glycosylation of the peptide backbone.