A vaccine that prevents HIV infection remains an important goal in the fight against AIDS, but the current top HIV vaccine candidates may not work in this way, say scientists at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH). Rather, the first successful preventive HIV vaccines, if administered prior to HIV infection, may reduce HIV levels in the body, thereby delaying the progression to AIDS and the need to start antiretroviral drugs. These vaccines may also reduce the chance that a person infected with HIV would pass the virus on to other people, according to NIAID Director Anthony S. Fauci, M.D., and Margaret I. Johnston, Ph.D., director of NIAIDs Vaccine Research Program in the Division of AIDS.

In a review article in the May 17 issue of the New England Journal of Medicine, Drs. Johnston and Fauci examine the daunting challenges posed by HIV, the evolution of HIV vaccine research, the role T cells may play in HIV vaccine effectiveness, and how the first successful HIV vaccine may fit into a comprehensive HIV/AIDS prevention effort.

Vaccines typically work by mimicking the effects of natural exposure to a specific microbe. Because of initial exposure, the immune system develops the ability to recognize the specific microbe and can protect the human body against it if it reappears. HIV, however, has thwarted scientists efforts thus far to develop a classic preventive vaccine for the virus because of its ability to integrate into target cells and evade clearance by the immune system. The interaction between HIV and the immune system is complex, and how different HIV-specific immune responses help to control infection is only partially understood.

"The development of an HIV vaccine is a complex research challenge because the virus is unusually well-equipped to elude immune defenses," says Dr. Fauci. "Much progress has been made; however, we must continue research eff
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Contact: Kathy Stover
kstover@niaid.nih.gov
301-402-1663
NIH/National Institute of Allergy and Infectious Diseases
16-May-2007