Abstract
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.