Because of the difficulty raising antibodies that are capable of totally blocking natural HIV-1 infections, the GeoVax vaccine approach has focused on raising cellular immune responses in addition to antibodies, which together can better control HIV-1 infections than either can alone.
Vaccine induced cellular immune responses are mediated by white blood cells in the body called T-cells that recognize and respond to the presence of foreign proteins presented by an infection such as the HIV-1 virus. CD8 T-cells directly combat these infections by destroying HIV infected cells, while CD4 T-cells provide growth factors that support activation and maintenance of CD8 T-cell responses.
Proteins produced in the cells of a person are the best substrates for raising CD8 T-cell responses. GeoVax vaccines are expressed in cells of the vaccinated person by genetically engineered DNA vaccines and live viral vector Modified Vaccinia Ankara (MVA) vaccines.
Our method of stimulating high T-cells frequencies and antibodies in the vaccinated person is to combine DNA vaccine priming with a recombinant live virus MVA vaccine boost. This prime/boost combination elicits protective immune responses in preclinical primate models and holds high promise for eliciting responses that will protect humans against the development of HIV/AIDS.
For a more in-depth analysis of HIV/AIDS, the disease and the work being done to combat it, visit the NIAID or IAVI (International AIDS Vaccine Initiative).