IL-12/GM-CSF Coadministration in an SIV DNA Prime/Protein Boost Protocol Enhances Gag-Specific T Cells but Not Virus-Specific Neutralizing Antibodies in Rhesus Macaques

Coadministration of pVecB7, a replication-defective SIV DNA vaccine, with interleukin-12 and GM-CSF expression plasmids, induced markedly enhanced control of viral replication and disease-free survival in macaques challenged intrarectally with pathogenic SIVsmE660. Protective mechanisms correlated with broader cell-mediated immune responses to the first two-thirds of the SIV Gag protein and possibly with enhanced SIVsmE660 antibody neutralization at set point, but not with pre- or early postchallenge SIVsmE660 neutralizing antibody production.