May 5, 2011

Gene Identified In Monkeys Protects Against AIDS

Some monkeys are born with a certain gene that boosts protection against simian immunodeficiency virus (SIV), a trait that could help researchers develop better AIDS vaccines, according to a study released Wednesday.

The researchers vaccinated a group of rhesus monkeys, and then repeatedly exposed them to SIV over the course of two weeks.  They found that while half of the monkeys became infected, the other half, which was more likely to express a certain gene known as TRIM5, did not.

The findings could help researchers develop a vaccine against human immunodeficiency virus (HIV), which causes AIDS, according to the study's lead author, Norman Letvin.

"It tells us -- probably much to our surprise -- that there will likely be in humans certain genes expressed by some people but not in others that may well be contributing to protection," Letvin, a professor at the Harvard Medical School, told the AFP news agency.

"So that we not only have to look at vaccine-induced antibody responses but we also have to look at the genetic makeup of the individuals who are being vaccinated because these data in monkeys suggest that both of these can be contributing."

A 2009 AIDS vaccine trial on humans in Thailand showed a 31.2-percent reduction in the risk of HIV.  However, the effectiveness declined after three years, Letvin said.

"We have demonstrated in the Thai vaccine trial that with existing technologies we see modest protection against HIV infections."

"If we couple that optimistic data in humans with the kind of data we generated in this study with monkeys, as well as other studies in monkeys, it suggests that if we can induce an even better antibody response through vaccination."

"Maybe with our next generation vaccine we can get that up to 50 percent or 60 percent or even higher levels of protection, and that protection can be even more durable."

Researchers continue to work towards an effective AIDS vaccine.  The virus has killed more than 25 million people worldwide since 1981, and has infected nearly 33 million people.

The study appears in the journal Science Translational Medicine. 


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