HIV-Tat Immunization Improves Effectiveness of cART Therapy

June 10, 2016

A recent 48-week phase II clinical trial evaluating patients with HIV in South Africa confirmed that the transactivator of transcription (Tat) vaccine against HIV/AIDS can improve responses to antiretroviral drugs.

Due to the different genetic backgrounds and infecting viruses of people with HIV, combined antiretroviral therapy (cART) is not always effective for restoring the immune system and eradicating the virus. The Tat vaccine was developed from anti-Tat antibodies that work by blocking the Tat protein to prevent immune dysregulation and the activation, entry, and spread of the HIV virus.

The randomized, double-blinded, placebo-controlled trial was conducted to evaluate the immunogenicity and safety of B-clade Tat (30 μg), given three times at 4-week intervals, in 200 HIV-infected adult volunteers on effective combined antiretroviral therapy (cART) with CD4+ T-cell counts ≥200 cells/µL.

After the evaluation period, the vaccine was found to be not only safe and well-tolerated but also effective for inducing durable, high titers of anti-Tat-B-clade antibodies in 97% participants. Additional results confirmed that the Tat vaccine increased CD4+ T-cell numbers of all participants tested, including those whose baseline levels were still low after years of therapy.

The study’s findings indicate that the Tat vaccine can restore the immune system in participants with different genetic backgrounds and infecting viruses, and supports the conduct of phase III studies for another sample in South Africa.



Ensoli B, Nchabeleng M, Ensoli F, et al. HIV-Tat immunization induces cross-clade neutralizing antibodies and CD4+ T cell increases in antiretroviral-treated South African volunteers: a randomized phase II clinical trial. Retrovirology. 2016;13:34.