[Search for a HIV vaccine]

A DIFFICULT SITUATION FOR A VACCINE: The human immunodeficiency virus has an exceptional capacity to mutate and macrophage reservoirs where it is harbored after penetration are highly inaccessible to antibodies. Use of a live vaccine would increase the risk of recurrent virulence and integration into the genome. UNKNOWN IMMUNOLOGY: Induction of cytotoxic cells appears to be essential, but investigations into this type of response are not well standardized and not easily quantifiable. Neutralizing antibodies would have a protective effect, but facilitating antibodies would have the opposite effect. SEVERAL POSSIBILITIES UNDER STUDY: These vaccine use live attenuated viruses with a more or less deleted genome, recombinant live viruses constructed from other viruses or bacteria, pseudo-particles, or recombinant proteins as well as vaccines synthetized from peptides or lipopeptides. An association of different vaccines would appear to be the best solution as live vectors usually induce cytotoxic cells while proteins or peptides induce production of neutralizing antibodies. RESPONSE TO VACCINES IS USUALLY WEAK: Both in animal models and in human volunteers, immune responses obtained to date have been quite variable and of short duration. Canarypox type recombinant vaccines followed by recombinant protein vaccines appear to give the best results at the present time. SEVERAL PROBLEMS: Anti-HIV vaccination protocols raise major ethical problems for the participating volunteers (ELISA test becomes positive, lack personal protection) and for the population involved in phase II/III trials. In addition, the virus rapidly penetrates via the mucosa without yielding sufficient mucosal immune response.