A vaccine containing a protein instrumental to HIV replication improves the overall effectiveness of antiretrovirals (ARVs). Publishing their findings in the journal Retrovirology, researchers in this Phase II clinical trial developed a vaccine that included a small amount of the protein Tat, an enzyme that fuels the virus’s lifecycle.

The researchers injected 168 HIV-positive participants with a vaccine that contained either 7.5 or 30 micrograms of Tat. Participants, all of whom were taking ARVs, were given the vaccine once a month for three or five months. Researchers followed the participants for three years.

The vaccine led participants’ immune systems to develop anti-Tat antibodies. The study members also experienced rising CD4 levels as well as higher levels of T, B and other immune cells. These effects lasted for the entirety of the study. The larger dose of the vaccine, when given over a three-month period, led to the greatest response.

The vaccine was also linked to a drop in HIV proviral DNA, an indication of a diminished viral reservoir. In order to deduce this fact, the researchers compared the participants to 79 people receiving just ARVs who were enrolled in a different observational study—in effect, a control group.

To read the press release on the study, click here.