Friday September 7, 2001

DNA-Based HIV Vaccine Slows Disease Progression

By Deborah Mitchell from Reuters


PHILADELPHIA (Reuters Health) - Patients with HIV given a new vaccine were able to keep levels of the virus in their blood down even after they stopped taking the potent cocktail of anti-AIDS drugs known as highly active antiretroviral therapy (HAART).

The 14 patients chosen for the study were selected because they had undetectable levels of HIV in their blood for 2 years. They had begun taking HAART about 90 days after becoming infected with HIV.

Dr. Martin Markowitz of the Aaron Diamond AIDS Research Center in New York City and colleagues used a recombinant DNA vaccine, ALVAC 1452 (Aventis Pasteur), which contained HIV DNA along with other fragments of the virus. They presented their findings here at the AIDS Vaccine 2001 meeting.

The patients were treated for 983 days, on average, receiving shots at the outset of the study and then 30, 90 and 180 days later.

Eleven of the 14 patients decided to stop taking HAART. They were compared with a "control'' group of five patients who did not receive the vaccine but did stop taking HAART.

Five of the 11 vaccinated patients, compared with one of the five control patients, maintained a 10-fold reduction in the level of HIV in their blood compared with their peak viral load after stopping HAART therapy.

Viral blood levels in the patients who responded to the vaccine took longer to climb after they stopped HAART, and also took longer to double. "That's critical,'' Markowitz said. "That is good evidence that HIV-specific immunity can affect virologic rebound after HAART.''

Importantly, all of the patients who rebounded had drug-susceptible virus, he pointed out.

"Even though we didn't completely control rebound, it opens the door to two avenues of research,'' Markowitz added. First, ''we have to optimize HAART to reduce residual viremia to lower levels.'' The next step is to "optimize the immunogenicity of this vaccine and other vaccines.''

HIV-infected patients "may benefit enormously from this type of manipulation. We just have to fine-tune this response,'' he said.

"We are planning to look at other immunogens to see if we can more effectively boost HIV-specific immune responses,'' Markowitz added.

The Aaron Diamond Center is also developing a DNA vaccine that they hope to begin testing in non-HIV-infected patients over the next year