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 [prevent AIDS] than either 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 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 monkey 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 vaccinology, visit the NIAID Vaccine site.