PROTECTION BY ATTENUATED SIMIAN IMMUNODEFICIENCY VIRUS IN MACAQUES AGAINST CHALLENGE WITH VIRUS-INFECTED CELLS

A vaccine against AIDS will probably have to protect against challenge both by viable virus-infected cells and by cell-free virus. Eight cyn omolgus macaques infected with attenuated simian immunodeficiency viru s (SIV) were challenged (four each) with cell-free and cell-associated SIV, All were protected, whereas eight controls were all infected aft er challenge. These findings show that live-attenuated vaccine can con fer protection against SIV in macaques, Extrapolation to human beings will require extensive evaluation of the safety of attenuated retrovir uses. Alternatively, the mechanism of this potent protection must be u nderstood and reproduced by less hazardous means.