Immune Responses Induced by Intramuscular Vaccination with rAAV2 and Pseudotyped rAAV1 Expressing HIV-1 gag
Immune responses against HIV-1 Gag resulting from recombinant adeno-associated virus serotype 2(rAAV2-gag) and pseudotyped AAV1(rAAV1-gag) by intramuscular vaccination were compared.At first,BALB/c mice were inoculated with 1×1011vg of AAV1-EGFP and AAV2-EGFP respectively.The expression of EGFP in muscle was detected under the long wavelenth UV lamp.Secondly,the codon-optimized HIV-1 gag gene was used to construct rAAV1-gag and rAAV2-gag.Gag expression was detected by indirect immunofluorescence assay and Western blot. BALB/c mice and rabbits were immunized with rAAV2-gag and rAAV1-gag in prime/boost scheme at week 0 and 3.The serum specific P24 IgG against HIV-1 Gag was detected by ELISA.Anti-Gag CTL response was detected by intracellular cytokine staining assay.The results showed that the level of EGFP expression was higher in BALB/c mice injected with rAAV1-EGFP than with rAAV2-EGFP.Gag expression was detectable in cultured cells infected with both rAAV2-gag and rAAV1-gag.Significantly higher level of anti-Gag IgG in serum was detectable in BALB/c mice and rabbits immunized with rAAV1-gag than that of animals immunized with rAAV2-gag.However,anti-Gag CTL responses in BALB/c mice were undetectable either with rAAV1-gag or with rAAV2-gag.The experiments suggested that rAAV1 and rAAV2 carrying HIV-1 gag mainly elicited humoral rather than cellular immune response,and rAAV1-gag elicited significantly higher level of anti-Gag IgG than rAAV2-gag in both BALB/c mice and rabbits.