New Hope for HIV Vaccine Research

By Troy Goodman

For nearly three decades, researchers have been trying to create an effective vaccine against human immunodeficiency virus (HIV)—without success. That’s why a vaccine trial in Thailand that demonstrated only limited efficacy made front-page news around the world last year. Now researchers at UAB’s Alabama Vaccine Research Clinic are testing a similar vaccine that could improve on the Thai results and offer new hope for at-risk populations.

In order to teach the immune system how to fight HIV, scientists need to find the right combination of identifying marks—genes or proteins from the virus’s inner core or outer shell, or both. Some infected patients naturally produce virus-fighting antibodies on their own, but this often occurs years after the initial infection, when it is too late to halt HIV’s eventual deadly grip.

The vaccine now being tested at UAB would essentially speed up that process, using a new combination of re-engineered genes to promote an earlier antibody response that could prevent infection. It could also act to keep HIV in check if an infection does occur. In the recent Thailand-based trial, volunteers who were vaccinated acquired HIV at a rate nearly one-third lower than those who received a placebo shot.

“The Thai trial showed some efficacy, and this UAB study may do the same thing. It may be even better,” says Paul Goepfert, M.D., director of the vaccine research clinic. UAB is testing HVTN 505, a vaccine sponsored by the National Institute of Allergy and Infectious Diseases. It comes as a four-shot regimen designed to drop recipients’ “viral load”—simply put, the amount of HIV detected in the blood—should they become infected. Like the vaccine tested in the Thai trial, it may even prevent infection completely.

Viral load is an important health indicator, Goepfert says, because HIV-positive patients who have less of the virus in their systems typically remain healthier for longer periods than those with higher viral levels. Ultimately, the goal is to enroll 1,350 sexually active gay and bisexual men age 18 to 45 in Alabama and 11 other sites in the trial.

“Clearly we still have a lot to learn in terms of what it takes to make an HIV vaccine,” Goepfert says. But preliminary evidence suggests that HVTN 505 “does induce better immune responses; it could not only prevent infection but also modulate infection after someone is exposed to the virus.” That’s good news for those fighting the AIDS epidemic, since HIV-infected individuals with reduced levels of virus may be less likely to transmit to others.