Single-dose HIV DNA vaccine induces strong immune response in monkeys

For the first time researchers from the U.S. and abroad have shown that a single-dose HIV DNA vaccine can induce a long-lasting HIV-specific immune response in nonhuman primates, a discovery that could prove significant in the development of HIV vaccines.

They detail their findings in the February issue of the Journal of Virology, ScienceDaily reported Feb. 24.

The control of HIV to substantially reduce viral loads and minimize transmission not only relies on the production of neutralizing antibodies, but also the development of high frequency, broadly targeted T-cell responses specific to the virus.

To date live-attenuated simian immunodeficiency virus (SIV)/HIV vaccines have prompted the most significant immune response against AIDS in a nonhuman primate model, but risk of redeveloping pathogenic forms makes them ineligible for human use.

In a previous study the researchers successfully induced long-lasting and potent HIV-specific immune responses in mice following immunization with a single-dose SHIV DNA-based vaccine.

In this study rhesus macaques were immunized with a single high dose of the SHIV DNA-based vaccine and monitored for vaccine-induced immune responses. Results showed that all immunized monkeys developed broad HIV-specific T-cell immune responses that persisted for months. Additionally, an unusual re-emergence in the blood following an initial decline and in the absence of antibody responses was noted.

"Our comprehensive analysis demonstrated for the first time the capacity of a single high dose of HIV DNA vaccine alone to induce long-lasting and polyfunctional T-cell responses in the nonhuman primate model, bringing new insights for the design of future HIV vaccines," the researchers said.