HIV infection is characterized by a long asymptomatic state during which the immune state of the infected individual is not clinically impaired. During this time, neutralizing antibodies may play an important role in controlling virus replication and thereby maintaining the disease-free state. The major neutralizing epitope of HIV is the highly variable V3 loop region of gpl20 while a weaker set of epitopes is in the conserved CD4-related region. For passive immunotherapy in AIDS, group-specific neutralizing antibodies are preferred. The aim of this project is to develop human group-specific neutralizing antibodies against a conserved CD4-related epitope. B cells obtained from the peripheral blood of HIV+ individuals will be enriched using anti-idiotypic antibodies previously shown to select for group-specific neutralizing antibodies. B cells from individuals with high titers of group-specific/Id+ antibodies will be clonally expanded using anti-CD3 activated T cells, a highly efficient B cell cloning system. B cell colonies producing antibodies of the appropriate specificity will be transformed using EBV to establish short-term clones which will be further evaluated. Immunoglobulin genes from B cells found to produce group-specific neutralizing antibodies will be cloned and expressed to produced antibody for clinical evaluation to be initiated during Phase II studies.