Can HIV infection be prevented with a vaccine?

The global human immunodeficiency virus type 1 (HIV-1) epidemic is devastating many communities and a well tolerated and effective vaccine is urgently required. Several lines of evident suggest that vaccine-induced protective immunity can be achieved. This evidence includes individuals shown to have natural immunity, and the partially effective immune responses that are generated during natural infection. However, the obstacles to HIV-1 vaccine development are enormous. The only substantially effective vaccine studied in pathogenic animal models (live, attenuated vaccines) is at present far too unsafe. The only HIV-1 vaccine to proceed to efficacy trials (an envelope protein approach) has been disappointing in its immunogenicity and efficacy in preliminary trials. The antigenic variability of HIV-1 strains is also a great obstacle. Unfortunately, commercial realities also do not favour the expensive development of HIV-1 vaccines required most urgently in less developed countries. Despite these obstacles, there is cause for cautious optimism. Better tolerated HIV-1 vaccine approaches are currently showing great promise in primate models and preliminary clinical trials. Many governments and the World Bank are now providing the political will and funding necessary to fast-track HIV-1 vaccine development. Given sufficient long term scientific and commercial commitment to the HIV-1 vaccine development process, it is ultimately likely that a preventative HIV-1 vaccine will emerge.