Infection of rats with bovine leukaemia virus: establishment of a virus-producing rat cell line.

Adult rats were infected with bovine leukaemia virus (BLV). Inoculated rats persistently produced antibodies directed against viral structural proteins. No major pathogenesis in infected rats was found during 2 years of observation. It was possible to recover the virus from rat spleen several months after infection. A cell line, R(BLV), was established from rat spleen; this contained integrated BLV provirus. R(BLV) cells kept for over 80 passages in vitro produced viral particles with the properties of BLV. Provirus reintegration and/or amplification occurred in R(BLV) cells. The cell line was found to be tumorigenic in rats, and the virus produced was immunogenic. R(BLV) cells represent the first described BLV-producing rat cell line. Proven persistent infection with BLV indirectly suggests that rats can serve as a reservoir of BLV in nature.