Mechanisms of protection against simian immunodeficiency virus infection.

One of the obstacles to the development of an effective AIDS vaccine has been the limited information on the mechanisms of protective immunity to HIV. In macaques, immunization with attenuated simian immunodeficiency viruses (SIV) has proved to be one of the most effective strategies to induce protection against infection or disease with pathogenic lentiviruses. Infection with attenuated SIV strains induces a broad range of SIV-specific immune responses, including relatively potent cytotoxic T lymphocyte (CTL) and antibody responses. Several studies of macaques vaccinated with attenuated SIV have demonstrated correlations between CTL responses or antibody responses and protection but more detailed studies are needed to document the relative importance of these responses in protective immunity.