HIV-1 env DNA vaccine administered to rhesus monkeys elicits MHC class II-restricted CD4+ T helper cells that secrete IFN-gamma and TNF-alpha.

The Th cell response elicited by an HIV-1 env plasmid DNA vaccine was assessed in rhesus monkeys by isolation of gp120-specific, MHC class II-restricted CD4+ T cell lines from PBL of vaccinated animals. The Env-specific CD4+ T cell lines recognized epitopes located in the second hypervariable region and in the carboxyl terminus of HIV-1 gp120. These cell lines proliferated in response to APC in the presence of recombinant gp120, as well as to APC expressing virally encoded Env. All of the CD4+ T cell lines responded to Env peptide by secreting IFN-gamma and TNF-alpha without appreciable IL-4 production. Recombinant gp120 stimulation of PBL from these vaccinated monkeys elicited the secretion of a similar profile of cytokines. Demonstration of a nucleotide vaccine eliciting a Th1-like immune response is consistent with the well documented ability of naked DNA vaccines to induce durable CD8+ CTL responses.