Current progress in the development of HIV vaccines.

The greatest hope for controlling the expanding HIV epidemic is the development of a preventive HIV vaccine. Despite almost twenty years of effort, the search for an effective HIV vaccine continues at the present time. Advances in the understanding of HIV immunopathogenesis, and especially viral immune evasion mechanisms, have provided important insights into HIV vaccine design. HIV vaccine approaches based solely on recombinant monomeric envelope glycoproteins have failed dramatically and have been discarded. Modern vector technologies with the potential for generating protective cellular immune responses against HIV are undergoing intensive evaluation in clinical trials. Adenoviral vector systems appear to be very promising for this purpose, while the ability of poxvirus-based regimens to elicit potent HIV-specific cellular immune responses in humans is less certain. A number of novel live vector-based approaches are in development. This review presents the current state of the HIV vaccine field, with an emphasis on those vaccines that are in clinical trials or in an advanced stage of preclinical testing. The HIV vaccine field is a very active and challenging one that will continue to push forward our understanding of basic immunology and drive the development of new vaccine technologies. New breakthroughs in methods to generate effective neutralizing antibody responses against HIV are urgently needed.