HIV pathogenesis and vaccine development.

Cautious optimism was a recurring theme of many of the AIDS vaccine-related presentations at the 13th annual Conference on Retroviruses and Opportunistic Infections. Several investigators suggested that the ability of HIV to escape cytotoxic T-lymphocyte responses may be more limited than previously thought, and encouraging results were presented regarding the ability of consensus ancestral sequences or polyvalent vaccines to increase the breadth of induced immune responses. A number of studies highlighted the potential efficacy of neutralizing antibodies: data from 2 groups suggested that neutralizing antibodies may play a role in preventing superinfection and previously unrecognized neutralizing epitopes were identified in the membrane proximal external region of envelope. Two studies documented that immunization with polyvalent simian immunodeficiency virus vaccines can induce sustained control of viremia following repeated low-dose mucosal challenge with pathogenic SIVmac strains and provided hope for the potential of T-cell-based vaccines to slow disease progression.