IMMUNIZATION OF ORAL MUCOSA FOR INDUCTION OF RECTAL AND GENITAL MOCOSAL IMMUNITY

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Like most other sexually transmitted diseases (STDs), HIV's primary site of infection is at mucosal surfaces, and like most other STDs, there is no vaccine for HIV. The proposed study will explore the possible use of the oral mucosal route for immunization against HIV/STDs through induction of immunity at distal sites mediated via the common mucosal immune system. We will characterize innate, adaptive cellular, and humoral responses in the periphery and in mucosal (oral, nasal, pulmonary and rectal) sites to vaccines given at 2 oral mucosal sites (submucosal immunization in the buccal fossa and over the lingual tonsil). Rhesus macaques will be immunized with an SIV version of one of the leading HIV vaccine regimens: DNA prime/replication-incompetent Ad5 vaccine boost. We will test whether submucosal immunization over the lingual tonsil produces robust peripheral B and T cell responses. Adaptive responses will be measured in the blood and at mucosal sites; antigen-specific T cells will be measured using ELISpot and intracellular cytokine staining and antibody will be measured by ELISA. Possible mechanisms underlying differences in adaptive responses elicited by different routes will be investigated via studies of innate immune responses (systemic dendritic cell phenotype and function, and serum cytokine/chemokine profiles). This study will provide data on whether vaccination of the oral mucosa can provide protection against sexually transmitted organisms, through induction of immunity at distal sites (such as the rectum) mediated by the common mucosal immune system. It will also investigate the usefulness of this route of immunization for protection against respiratory pathogens, such as influenza, when immunity in the nose and lungs is desired. DNA priming elicited low to undetectable vaccine-specific cellular responses in blood. However, in bronchoalveolar lavage (BAL) high frequency polyfunctional SIV-specific CD4+and CD8+T cells were detected by ICS in DNA-primed IT animals, although DNA-primed IM animals showed very low frequency responses. CM9 gag tetramer responses were significantly higher in the IT group (P0.005). SIV-specific antibody responses in plasma were similar for IT and IM groups, but showed distinct kinetic profiles. Responses were significantly increased after boosting with rAd5; the IT group generated relatively stronger cellular responses in blood, but the difference in magnitude of responses by group was not statistically significant (%CM9+CD8+cells; IT=3.2%, IM=2.3%). High-level CD8+responses were seen at mucosal sites in the IT group (%CM9+CD8+cells: BAL=11.8%, colon=1.5%). Tonsillar immunization can elicit systemic responses and mucosal responses at distant sites. Further characterization of mucosal responses, including protection from low-dose rectal challenge with SIVmac239, is in progress.