Simian Immunodeficiency Virus (SIV) is a primate retrovirus which causes an immunodeficiency syndrome similar to Acquired Immunodeficiency Syndrome of man. The striking similarities between this virus and the human immunodeficiency virus (HIV) in terms of both viral structure and resultant clinical disease make it an attractive model for studying methods by which immunity to retroviruses can be enhanced. Early trials with dead virus vaccines have been disappointing. Murine models of lethal infection have suggested that antibodies made to virus specific antibodies or virus specific T cells may themselves (without antigens) be capable of stimulating immunity against lethal infections. This grant will involve a quantitative analysis of the T cell response to SIV. In addition, monoclonal antibodies to virus specific antibodies and T cell clones will be prepared and tested as inducers of immunity.