HIV Vaccine Development.

Several interesting new vaccine-related studies were presented at the 16th Conference on Retroviruses and Opportunistic Infections this year. Transmitted viruses appear to be derived from cell-free virus rather than cell-associated virus, at least in men who have sex with men. Follow-up studies from the Step (HIV Vaccine Trials Network 502) trial indicated that if individuals mounted certain vaccine-induced responses, they may control viral replication after infection. Finally, adeno-associated-virus-derived neutralizing antibodies completely protected macaques from infection, suggesting novel mechanisms of viral control.