Injection of rabbits with a human T-cell line that has been infected 6 with HIV-1 causes seroconversion within 4 weeks of injection. Normally, 5 x 10(6) cells are administered, if higher doses are used, the seroconversion occurs earlier and the levels of antibody are elevated. One hundred and thirty rabbits have been successfully infected. Five percent of the animals did not seroconvert after the original dose of infected cells, but antibody could be detected by following a booster injection. Virus has been detected by polymerase chain reaction amplification of viral DNA and RNA in brain as well as lymphoid tissues. Immune responses to tetanus toxoid and to BCG have been monitored in infected animals and were shown to be diminished or absent.