Strong IgA-mediated mucosal immune responses elicited in BALB/c mice primed with Vaccinia Tiantan-based HIV vaccine intramuscularly and boosted with protein intranasally

Objective To analyze the mucosal immune responses induced in BALB/c mice after immunization with Vaccinia Tiantan-based HIV vaccine in combination with protein and to evaluate the efficacy of different immune strategies and adjuvants. Methods The BALB/c mice were intramuscularly or intranasally immunized with the recombinant Vaccinia virus Tiantan strain (rTV) carrying CN54 Gag-Pol-Env gene and boosted with the gp140 protein and MF59 adjuvant by intramuscular, intranasal or subcutaneous injection. Serum, saliva and vaginal lavage samples were collected from the BALB/c mice. The titers of antigen specific IgG and IgA were detected by ELISA. Results Significantly enhanced mucosal immune responses were induced by immunization with gp140 protein used in combination with MF59 adjuvant. The IgA antibodies elicited in mice mucosal tissues by gp140 protein and MF59 adjuvant were as high as those induced by gp140 protein and cholera toxin subunit B or recombinant flagellin adjuvant. High tiers of gp140-specific IgA antibodies were observed in serum, saliva and vaginal lavage samples from the mice intramuscularly primed with rTV and intranasally boosted with gp140 protein and MF59 adjuvant. The tiers of IgA antibodies in serum and mucosal tissue samples were 1∶15 000 and 1∶600, respectively. Conclusion High titers of mucosal IgA antibodies were elicited in BALB/c mice intramuscularly primed with Vaccinia Tiantan-based HIV vaccine and intranasally boosted with gp140 protein and MF59 adjuvant, especially in vaginal and oral tissues. This immunization strategy might be able to block the heterosexual transmission of HIV-1 through vaginal and oral mucosa. Key words: HIV Vaccine; Vaccinia Tiantan strain; HIV protein vaccine; Mucoantibody