DNA vaccine expressing HIV-1 gp120/immunoglobulin fusion protein enhances cellular immunity

In this study, we explored the possibility of augmenting human immunodeficiency virus (HIV) gp120-specific cell-mediated immune responses in mice by means of a DNA vaccine encoding a mouse Ig Fcγ2a fragment fused with gp120 (gp120-Ig, Ig-gp120). Western blotting analysis revealed that the HIV gp120 protein expression efficiency was higher in cells transfected with the gp120-Ig-coding plasmid (pGp120Ig) than in those transfected with the gp120 and Ig-gp120 expression plasmids (pGp120 and pIgGp120, respectively). pGp120Ig elicited more HIV-specific CD8 T cells and effector memory CD8 T cells than pGp120 in immunized mice. Furthermore, pGp120Ig significantly reduced the viral load after challenge with an HIV Env gp160-expressing vaccinia virus. These results demonstrate that covalent antigen modification with an Ig sequence can modulate antigen-specific cellular immune responses. The approach may be useful for vaccine development.