By Maggie Fox, Health and Science Editor
WASHINGTON (Reuters) - AIDS experts and advocates gathering in Vienna this weekend for a conference on the pandemic will hear about progress in protecting people from the deadly virus using drugs, and ways to affect behavior.
No breakthrough news is expected on a vaccine. But researchers are more hopeful than they have been in years that it may be possible.
They just have to choose the best path to pursue.
"There has been a renaissance in AIDS vaccines," says Dr. Seth Berkley, president of the International AIDS Vaccine Initiative.
Two studies published in the past year have greatly raised hopes. In one published last September, a combination of two older vaccines lowered the infection rate by about a third after three years among 16,000 ordinary Thai volunteers.
In a second study, published earlier this month, researchers discovered human antibodies that can protect against a wide range of AIDS viruses. [ID:nN08226714]
"I am more optimistic about an AIDS vaccine at this point in time than I have been probably in the last 10 years," Dr. Gary Nabel of the U.S. National Institute of Allergy and Infectious Diseases, who led the second study, said.
The AIDS virus infects 33.4 million people globally, according to the United Nations agency UNAIDS. It has killed more than 25 million people.
Because it is spread in so many ways -- during sex, on needles shared by drug users, in breast milk and in blood -- there is no single easy way to prevent infection. A vaccine is the best hope.
The recent research has helped narrow down where scientists need to concentrate, Berkley says.
One route may be to redesign the Thai vaccine trial and make the vaccine work better.
That vaccine is a combination of Sanofi-Pasteur's ALVAC canarypox/HIV vaccine and the HIV vaccine AIDSVAX, made by a San Francisco company called VaxGen and now owned by the nonprofit Global Solutions for Infectious Diseases.
It may be easier to see results if the vaccine is tested in people at higher risk of infection than the Thai volunteers were.
YEARS MORE TESTING
Some kind of vaccine is likely to be tested in South Africa, where HIV infects up to 50 percent of some populations, by 2013 or 2014, Berkley said. But testing takes years and five years down the road researchers may have yet another vaccine that does not work.
This has scared off most big drug companies, who are leaving the research to non-profits like Berkley's IAVI, governments, and small biotech companies.
With money tight, the research must be focused. The best hope, said Berkley, is a vaccine that can activate immune system proteins called neutralizing antibodies.
That is why researchers are so excited about Nabel's results this month at the U.S. National Institutes of Health.
They found the antibodies in the blood of some people whose bodies made them after they were infected with HIV. Two of them attached to and neutralized 90 percent of the various mutations of HIV.
The researchers froze one of the antibodies in the process of attaching to and neutralizing the virus, getting an atomic-level image in a process called x-ray crystallography.
Being able to "see" what the structure looks like could enable researchers to design a vaccine using a process called rational vaccine design, akin to an established technique for making drugs called rational drug design, Nabel said.
A few small biotech companies believe they may also have answers. Norway's Bionor has been testing a vaccine called Vacc-4x, made out of peptides, little pieces of protein from the AIDS virus.
Bionor does not plan to develop the vaccine to protect people from HIV, but as a way to give them a break from the AIDS drug cocktails called highly active antiretroviral therapy or HAART.
Seven years after vaccinating HIV patients, they still made antibodies against the virus, Dr. Per Bengtsson, Bionor's senior vice president, told Reuters in a recent interview. Details of more study will be presented at the AIDS meeting in Vienna next week.
Amsterdam-based Crucell NV is another example. The company is in early stages of human testing of a vaccine made using a virus that carries pieces of HIV DNA.
But the road is littered with the remains of failed vaccine attempts. In 2007, Merck & Co ended a trial of its vaccine after it was found not to work, and in 2003, AIDSVAX used alone was found to offer no protection, either.
(Editing by Eric Walsh)