DETECTION OF A NOVEL BOVINE LYMPHOTROPIC HERPESVIRUS

Degenerate PCR primers which amplify a conserved region of the DNA pol ymerase genes of the herpesvirus family were used to provide sequence evidence for a new bovine herpesvirus in bovine B-lymphoma cells and p eripheral blood mononuclear cells (PBMC). The sequence of the resultan t amplicon was found to be distinct from those of known herpesvirus is olates. Alignment of amino acid sequences demonstrated 70% identity wi th ovine herpesvirus 2, 69% with alcelaphine herpesvirus 1, 65% with b ovine herpesvirus 4, and 42% with bovine herpesvirus 1. Phylogenetic a nalysis placed this putative virus within the tumorigenic Gammaherpesv irinae subfamily, and it is tentatively identified as bovine lymphotro pic herpesvirus. This novel agent was expressed in vitro from infected PBMC, and cell-free supernatants were used to transfer infection to a bovine B-cell line, BL3. Analysis, with specific PCR primers, of DNA from bovine PBMC and lymphoma cells identified infection in blood of 9 1% of adult animals (n = 101), 63% of lymphomas; (n = 32), and 38% of juveniles (n = 13). Of the adults, herpesvirus infection was present i n 94% of animals that were seropositive for bovine leukemia virus (BLV ) (n = 63) and in 87% of BLV-seronegative animals (n = 38). Of the ser opositive group, 17 animals exhibited persistent lymphocytosis, and 10 0% of these were herpesvirus positive by PCR. A role for bovine lympho tropic herpesvirus as a cofactor in BLV pathogenesis is considered.