WASHINGTON, DC – According to research published in the journal Science on June 9, HIV/AIDS researchers have developed a vaccine that helps prolong survival in monkeys post-infection. Although the vaccine does not create immunity from the virus, researchers say it could lead to treatment in humans that would allow already-infected individuals to live longer without becoming sick.Meanwhile, several clinical trials using human volunteers spearheaded by the HIV Vaccine Trial Network (HVTN) continue to make advances in efforts to produce DNA-based vaccines. Hospitals such as the Miriam Hospital in Providence, RI, as well as health centers in Boston, MA and New York, NY are in the early phases of programs using HIV-negative human subjects to test such DNA-based vaccines.
Dr. Norman Letvin of Harvard Medical School, one of the leaders of the research team that published their results in Science last week, told Reuters that “A vaccine of this type does not appear to prevent infection,” but added that a similar vaccine could help extend the lifespan of infected people and delay onset of some AIDS symptoms.
Dr. Letvin’s research team conducted experiments in which they vaccinated monkeys against simian immunodeficiency virus (SIV), using the closest model to human infection possible.
The Monkeys who received the SIV vaccine lived close to three times longer after being infected with the virus, surviving up to 900 days, while the monkeys that were not vaccinated lived an average of only 300 days, according to the research published in Science.
Letvin told Reuters his team’s trial will prove useful to researchers working with humans, by giving researchers something to keep their eye on in human volunteers – volunteers who cannot be infected with the AIDS virus intentionally, as the monkeys in Letvin’s trial were.
Letvin noted that there are “two human vaccines that are similar to this that are now going forward into advanced efficacy trials.”
One such vaccine is under development by the U.S. National Institutes of Health and the other by major pharmaceutical company Merck and Co.
Dr. Melissa Gaitanis, who heads up the human research being conducted at Miriam Hospital along with fellow researcher Dr. Michelle Lally, recently explained the basics of their groups’ efforts to EdgeBoston.com.
“Basically, they have this DNA technology where they manufacture in the lab pieces that are similar to the genetic pieces of actual HIV. So they take [synthetic versions of] proteins that are inside the virus and the outer coating, the envelope, and stick these manufactured DNA particles in a vehicle, often times a viral vector, like the Merck product,” which uses adenovirus, which is similar to the common cold, Gaitanis said.
A “viral vector” is a delivery medium used to insert genetic material into a person’s cells.
“(T)he body still sees it [the introduced genetic material] like a virus,” said Gaitanis. “So they put these particles in there so that, when you’re delivering it, the body identifies the adenovirus as foreign and it reacts against that in such a way that it’s boosting its reaction against those DNA particles.”
Gaitanis said that one of the hardest parts of conducting the trials is overcoming the fear that some people feel about getting sick from the tests themselves or being stigmatized due to participation in the trials.
“It’s hard to get people in,” Gaitanis told EdgeBoston.com. “Some of the reasons are the stigma that surrounds HIV, and people feel that they’re going to get HIV from the vaccine, or they’re going to be perceived as HIV-positive if they go for any of these trials.”
Gaitanis said, however, that the trials are conducted anonymously and that the risk of the experimental AIDS vaccines is the same as with other vaccines, and are relatively minor. The most serious problems involve reactions at the injection site involving pain or tenderness, occasional fever, fatigue and other common vaccine side effects.
For more information on AIDS vaccine trials, visit the HVTN website at http://www.hvtn.org and the work of the Aids Clinical Trials Group (ACTG) at http://www.aactg.org.
