DNA inoculation induces cross clade anti-HIV-1 responses.

Nucleic acid or DNA immunization represents a novel approach to vaccine and immune therapeutic development. The direct injection of expression cassettes into a living host results in in vivo gene expression and immune activation. In the case of HIV-1 it has been shown by our laboratory that facilitated injection mimicks aspects of live attenuated vaccines and that both humoral and cellular responses can be induced upon injection of a nucleic acid sequence directly into a host target tissue. Antisera from HIV-1 plasmid expression cassette-immunized animals contain anti-HIV envelope glycoprotein immune responses. The antiserum neutralizes HIV-1 infection and inhibits cell to cell infection in vitro. Cellular immune responses have also been evaluated. We observed both T cell proliferation and isotype switching consistent with the production of relevant T helper immune responses in immunized animals. Furthermore it was demonstrated that CTL lysis of relevant env-expressing targets was similarly induced. These studies further define the importance of evaluating this new technology for vaccine and immune therapeutic development for HIV-1 as well as for other human viral pathogens.