Current efforts on generation of optimal immune responses against HIV through mucosal immunisations

Currently, over 40 million HIV-infected individuals are found around the globe, with an additional 15,000 daily infections. There is a general consensus that the most effective way to prevent new infections is to introduce a prophylactic vaccine. It is also generally agreed that both cytotoxic T lymphocytes (CTLs) and neutralising antibodies are important to mediate protection. The neutralising antibodies must be broadly reactive to neutralise multiple primary isolates. There is also increasing agreement that CTLs and neutralising antibodies should be present at mucosal sites of HIV entry, the draining lymph nodes and systemically. The route of immunisation is important when determining the site where protection is desired, i.e. the female genitourinary tract versus the male or female rectum versus systemic tissues, as are the type of HIV-related antigens, immunopotentiating adjuvants and delivery systems. Finally, multiple vaccine delivery systems may be required to be administered through both mucosal and parenteral routes to induce optimal immune responses and protection against HIV infection through rectal, vaginal or systemic routes of transmission. This review discusses current efforts on the generation of optimal immune responses against HIV in the genitourinary and intestinal tracts using mucosal immunisations alone or combinations of mucosal and parenteral immunisations.