Induction of mucosal homing virus-specific CD8+ T lymphocytes by attenuated simian immunodeficiency virus

Induction of virus-specific T-cell responses in mucosal as well as systemic compartments of the immune system is likely to be a critical feature of an effective AIDS vaccine. We investigated whether virus-specific CD8(+) lymphocytes induced in rhesus macaques by immunization with attenuated simian immunodeficiency virus (SIV), an approach that is highly effective in eliciting protection against mucosal challenge, express the mucosa-homing receptor alpha 4 beta 7 and traffic to the intestinal mucosa. SIV-specific CD8(+) T cells expressing alpha 4 beta 7 were detected in peripheral blood and intestine of macaques infected with attenuated SIV. In contrast, virus-specific T cells in blood of animals immunized cutaneously by a combined DNA-modified vaccinia virus Ankara regimen did not express alpha 4 beta 7. These results demonstrate the selective induction of SIV-specific CD8+ T lymphocytes expressing alpha 4 beta 7 by a vaccine approach that replicates in mucosal tissue and suggest that induction of virus-specific lymphocytes that are able to home to mucosal sites may be an important characteristic of a successful AIDS vaccine.