MACROPHAGES INFECTED WITH BOVINE LEUKEMIA-VIRUS (BLV) INDUCE HUMORAL RESPONSE IN RABBITS

BLV is a lymphotropic retrovirus which infects mainly B-cells. However , the possible infection of cells of the monocyte/macrophage lineage ( M/M) might explain some aspects of the disease such as latency or dise ase progression. We infected sheep M/M with BLV either by culturing M/ M with supernatant containing virus, or coculturing M/M with persisten tly infected cell lines. These BLV-infected M/M were inoculated into r abbits and the serological response was followed for two years, ELISA results using adsorbed sera showed a persistent production of specific antibodies from as early as the first week post inoculation. Two test s were used to detect the response against envelope glycoprotein gp51: Agar gel immunodiffusion (AGID) and a virus neutralization test read as syncytia inhibition (SI). Sera were positive by AGID after the seco nd or third inoculation, Neutralizing titres (SI) were higher than tho se seen in control rabbits inoculated with persistently infected cell lines, suggesting that the virus may be expressed batter in M/M. Gag-r elated proteins were analyzed by Western Blot (WR). Sera from rabbits inoculated with BLV-infected M/M recognized as many viral proteins as sera from BLV immunized control rabbits or infected cows, and this pro file did not change with repeated inoculations, All these results sugg est that BLV may infect M/M, where viral proteins are actively express ed to the point that they induce a humoral immune response in animals, and that animals get persistently infected. (C) 1997 Elsevier Science B.V.