A revised version of the HIV vaccine that demonstrated modest protection among people in Thailand protected more than half of monkeys from an HIV-like virus in a recent study.

In 2009, a Phase III trial of the so-called RV144 HIV vaccine demonstrated a 31 percent risk reduction in Thai volunteers. Research teams have sought to build on that success in the years since, including those behind a major Phase III HIV vaccine trial that recently began testing a modified version of RV144.

Publishing their findings in Nature Communications, researchers in this new primate study added three additional targets to RV144’s two targets in hopes of prompting a greater antibody response to SHIV, a scientist-created virus that combines parts of the genomes of HIV and SIV, HIV’s simian cousin, for use in research.

The retooled vaccine reduced the risk of SHIV infection among the monkeys by 55 percent.

Next, the scientists hope to determine which of the additional targets helped increase the vaccine’s efficacy.

To read a press release about the study, click here.

To read the study, click here.