Monkeys Immune to AIDS

Some monkeys born with gene that protects against AIDS
Thu, May 5, 2011

A certain gene in some monkeys can help boost vaccine protection against simian immunodeficiency virus (SIV), a trait that could help researchers develop better AIDS vaccines for humans, suggested a study out Wednesday.

Researchers vaccinated a large group of rhesus monkeys and then exposed them to SIV repeatedly over the course of two weeks. Half became infected, but the other half did not.

Those who resisted infection were more likely to express a certain gene, identified as TRIM5.

The findings could help researchers in the elusive search to develop a vaccine against human immunodeficiency virus (HIV), which causes AIDS, said 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," said Letvin, a Harvard Medical School professor.

"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."

The study appears in the journal Science Translational Medicine.

A 2009 AIDS vaccine trial on humans in Thailand showed a partial shield against HIV -- 31.2-percent reduction in the risk -- but effectiveness dropped after three years, Letvin said.

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

"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," he said.

The quest continues for a vaccine against AIDS, which has claimed more than 25 million lives since 1981 and infected some 33 million people worldwide.

Source here

AIDS vaccine researcher hopeful

April 24, 2010

JOHANNESBURG: A leader in the search for a vaccine against HIV, which causes AIDS, said that recent advances have given scientists new reason for hope.

In an interview with The Associated Press on Friday, Dr. Alan Bernstein, executive director of the Global HIV Vaccine Enterprise, cited the world's first successful test of an experimental AIDS vaccine.

In September, researchers said the vaccine protected one in three people from getting HIV in a large study in Thailand.

Bernstein also pointed to recent progress in determining whether people with HIV produce antibodies that could lead to a vaccine guarding against a variety of forms of HIV.

He also said there is progress in mapping the many variations of what he called a "clever virus" that has so far eluded vaccine efforts because it kills some of the key cells needed to make a vaccine.

"This is a very exciting time in the field," Bernstein said. "A vaccine is possible, and we have the scientific tools now to turn that possibility into a reality."

Though he said the research effort has turned a corner after several setbacks, he cautioned a vaccine was still several years away.

Others are far less optimistic.

"I wish I could say I was. But I'm not," said Salim Karim, director of the Centre for the AIDS Programme of Research in South Africa.

"It's proving to be a challenge that's more complex than previously thought," he said, adding he has spent 15 years researching a vaccine, and expected success to take at least another 15.

Karim called the Thai study a "glimmer." Scientists must now try to improve the vaccine so that it protects more than a third of the people who get it, and lasts for more than the six to 12 months it now appears to be effective.

Questions have been raised about whether an HIV vaccine was possible, and even whether it made sense to devote time and energy to the pursuit.

Bernstein said a comprehensive approach, that includes finding a vaccine, must be taken against AIDS.

As head of an international group of major vaccine researchers and funders, Bernstein was in South Africa to discuss strategy with UN health and AIDS officials.

South Africa, a country of some 50 million, has an estimated 5.7 million people infected with HIV, more than in any other country.

In an announcement that marked a dramatic shift from the past, South African President Jacob Zuma pledged on World AIDS Day last year to embark on earlier and expanded treatment for HIV-positive South Africans. The program was to be formally launched this weekend.

Bernstein said a vaccine would be particularly important for Africa, where prevention and treatment campaigns have proven costly. A vaccine, unlike an expensive lifetime regime of AIDS drugs, would be administered every few years.

A vaccine "is the most effective public health measure we've come up with," Bernstein said.

The International AIDS Vaccine Initiative, which focuses on research into vaccines against strains of HIV that are prevalent in the developing world, says a vaccine must be part of a comprehensive solution. It says "no major viral epidemic has even been defeated without a vaccine."

According to a new report summarizing findings presented at a 2009 conference of vaccine researchers, the vaccine hunt is "steadily moving ahead," though HIV presents tough challenges.

The report in the May issue of The Lancet Infectious Diseases journal says that the massive, international effort to find an AIDS vaccine has had important side effects, providing information for the development of other vaccines and treatment for other diseases. - AP