OBJECTIVE: To investigate to ability of a genetically altered bacterial vector to stimulate mucosal and humoral immunity against envelope proteins of simian immunodeficiency virus. RESULTS A recombinant strain of Salmonella typhimurium that expresses p27 was tested to determine if it would stimulate immunological memory and facilitate antibody responses against envelope proteins. Gut exposure to this strain of S.t. was sufficient to augment immunity, also demonstrating the important relationship beween the mucosal and humoral immune compartments. FUTURE DIRECTIONS Having established that this bacterial vector elicits immunological memory against envelope proteins it would be important to determine whether this vaccine strategy is sufficient to promote protective immunity. In addition, it will be important to verify that the attenuation process is stable and that the bacteria is not prone to mutate in the gut environment. KEY WORDS SAIDS, mucosal immunity, Salmonella typhimurium, vaccine