Broad HIV-1 Neutralizing Antibody Response Induced by Heterologous Gp140/Gp145 DNA Prime-Vaccinia Boost Immunization

Abstract Objective To develop an effective HIV vaccine strategy that can induce cross-reactive neutralizing antibody. Methods Codon-optimized gp140 and gp145 env genes derived from HIV-1 cn54 , a CRF07 B′/C recombinant strain, were constructed as DNA and recombinant Tiantan vaccinia (rTV) vaccines. The effect of heterologous immunization with gp140 and gp145 was tested in mice and guinea pigs. T cell responses were detected using the IFN-γ ELISPOT assay. A panel of primary isolates of clade B′ and B′/C HIV-1 and TZM-bl cells was used to determine the neutralizing activity of immunized sera. Results The neutralizing antibodies (NAbs) induced by the heterologous immunogen immunization neutralized all HIV-1 B′ and B′/C primary isolates in the guinea pig model. Gp145 and gp140 heterologous prime-boost induced the best neutralizing antibody response with a broad neutralizing spectrum and the highest titer of 1:270 at 6 weeks after the last inoculation. However, the T cell response to HIV-1 peptides was significantly weaker than the gp145 + gp145 homologous prime-boost. Conclusions This heterologous prime-boost immunization strategy could be used to design immunogen-generating broad neutralizing antibodies against genetic variance pathogens.