Investigation of synergistic effects of β-defensin, vesatolimod and resiquimod in increasing the potency of a therapeutic HIV-1 vaccine candidate.

Abstract

Improvement of therapeutic vaccination strategies is critical to control the human immunodeficiency virus-1 (HIV-1) infection. The goal of this study is to determine the immunostimulatory effects of toll-like receptor (TLR) agonists including β-defensin (TLR4 agonist), vesatolimod (GS-9620: TLR7 agonist) and resiquimod (R848: TLR7/8 agonist) as individual or combined with the Nef^mut-Tat antigen candidate in BALB/c mice. The results of immune responses for groups receiving the recombinant Nef^mut-Tat protein (∼ 35 kDa) and the recombinant β-defensin-Nef^mut-Tat protein (∼ 45 kDa) showed that the linkage of β-defensin to Nef^mut-Tat protein could significantly increase the secretion of IFN-γ, TNF-α and Granzyme B. Furthermore, the highest levels of IFN-γ, TNF-α and Granzyme B was observed in group receiving β-defensin-Nef^mut-Tat protein + GS-9620 + R848 regimen indicating the potent synergistic effects of TLR agonists on induction of cellular immunity (i.e., stimulation of T-helper 1 cells and cytotoxic T lymphocytes). This regimen could significantly induce IFN-γ and TNF-α in splenocytes infected with single-cycle replicable (SCR) HIV-1 in vitro, as well. It was interesting that no significant differences in TNF-α and Granzyme B secretion were observed between groups receiving β-defensin-Nef^mut-Tat protein + GS-9620 and β-defensin-Nef^mut-Tat protein + R848; although group receiving β-defensin-Nef^mut-Tat protein + R848 could significantly induce IFN-γ secretion in uninfected and infected splenocytes compared to group receiving β-defensin-Nef^mut-Tat protein + GS-9620. These findings demonstrated that the simultaneous use of TLR 4, 7 and 8 agonists could improve and maintain cellular immunity against SCR HIV-1 infection suggesting an effective approach for eradication of latent HIV reservoir.