Current advances and challenges in HIV-1 vaccines.

Recent advances in science, which have aided HIV-1 vaccine development, include an improved understanding of HIV-1 envelope structure and function, expansion of the pipeline with innovative vaccine strategies, promising multi-gene and multi-clade vaccines that elicit cellular immunity, conduct of clinical trials in a global network, and development of validated techniques that enable simultaneous measurement of multiple T cell vaccine-induced immune responses in humans. A common feature of several preventive vaccine strategies now in early clinical trials is their ability in nonhuman primates to attenuate clinical disease rather than completely prevent HIV-1 infection. One vaccine concept has been tested in large-scale clinical trials, two are currently in efficacy trials, and one more is poised to enter efficacy trial in the next few years.