Mucosal administration of completely non-replicative vaccinia virus recombinant Dairen I strain elicits effective mucosal and systemic immunity.

We studied the immunogenicity of completely replication-deficient vaccinia virus Dairen I strain recombinant encoding simian immunodeficiency virus (SIV) gag/pol (rDIs) in both mucosal and systemic compartments. When administered either intranasally or intragastrically, rDIs elicited enhanced levels of both SIV Gag p27-specific IgA antibodies and specific plasma antibodies, and the enhanced immunity persisted for the 1-year of observation by intranasal immunization. Increases were observed in antigen-specific IgA antibody-forming cells (AFC) in intestinal mucosal tissues and in IgG AFC in spleens. Furthermore, induction of type 1 and 2 helper cytokines in CD4+ spleen T cells and of CD8+ IFN-gamma spot-forming cells in mucosal tissues was observed in the intranasally immunized mice. Moreover, not even high-dose rDIs generated an SIV gene signal in the brain tissues of immunized mice. These findings suggest that mucosal immunization with the DIs recombinant hold promise as a safe mucosal vector.