A reverse transcriptase assay for detection of the bovine leukemia virus.

An RNA-dependent DNA polymerase or reverse transcriptase has been demonstrated in highly purified bovine leukemia virus (BLV) particles. The viral enzyme responded very effectively to the exogenous template primer polyneucleotide (poly) (rA)-oligonucleotide (oligo) (dT). Unlike the reverse transcriptases of most mammalian C type RNA viruses, and of the ubliquitous foamy-like bovine syncytial virus, the BLV enzyme prefers magnesium rather than manganese for optimal activity. The identification of several other conditions required for optimal activity of the viral reverse transcriptase led to the development of a rapid, sensitive, semiquantitative assay, which is comparable in sensitivity to the syncytia-infectivity assay for the detection of BLV in supernatant fluids of monolayer cell cultures. However, the reverse transcriptase assay is not sufficiently reproducible for obtaining routine detection of BLV in short-term cultures of bovine peripheral blood lymphocytes. Therefore, this assay does not seem to provide an accurate method for the diagnosis of BL virus infection in cattle.