Heat shock proteins as vaccine candidates

Parasite heat shock proteins are phylogenetically well-conserved antigenic mosaics that nonetheless stimulate both humoral and cellular immune responses during the course of infection. These range from highly specific to broadly cross-reactive, with intermediate degrees also documented. The latter may prove beneficial, if they can be appropriately channelled to protect against multiple pathogens, or potentially harmful, if they cross-react with host components. Assessment of heat shock proteins as vaccine candidates has thus proceeded cautiously, with efforts being made to map the specificity of host immune responses to individual epitopes of the molecules. Ultimately, to serve as vaccines, the molecules must be recognized by the immune system within the context of a living pathogen, and be capable of inducing appropriate cellular and/or humoral immune responses that are effective at preventing establishment of individual pathogens. Reviewed are studies relevant to the use of parasite hsps as vaccine components, with emphasis on those from schistosomes, malaria, chlamydial, and mycobacterial parasites.