AIDS vaccination studies using feline immunodeficiency virus as a model: immunisation with inactivated whole virus suppresses viraemia levels following intravaginal challenge with infected cells but not following intravenouschallenge with cell-free virus

The feline immunodeficiency virus (FIV) provides an excellent model system for AIDS vaccination studies. In the present experiments we investigated th e immunogenicity and the protective activity of two inactivated vaccines pr epared from a primary virus isolate. One vaccine was composed of whole viru s inactivated with paraformaldehyde and then purified (WIV) and the other o f viral proteins extracted with Tween-ether (TEV). Both vaccines elicited r obust antiviral responses, but neither conferred appreciable levels of resi stance against systemic challenge with the homologous virus. In addition, w e tested whether the WIV vaccine, that had appeared more immunogenic, could protect against nontraumatic intravaginal exposure to FIV-infected cells. Although the proportions of control and vaccinated animals that became infe cted following mucosal challenge were similar, the vaccinees had significan tly lower viral burdens than the controls: thus suggesting that immunisatio n with the WIV vaccine had limited FIV replication following intravaginal c hallenge. (C) 1999 Elsevier Science Ltd. All rights reserved.