by Staff Writers
Washington (AFP) May 29, 2011
The race to end AIDS has picked up momentum in the past two years as scientific advances offer new hope of halting the spread of the disease nearly three decades after the epidemic surfaced.
Human immunodeficiency virus is well known to attack the body's natural defenses, but it has proven such a wily foe over the past 30 years because of the way it transforms, replicates and hides inside the body.
Scientists are learning more about how the virus infiltrates cells, and how to harness the body's own natural defenses to guard against it in the hope of closing in on new vaccines, strong prevention treatments and possibly, a cure.
"We have seen the light at the end of the tunnel," said Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases and a longtime leader in the fight to end AIDS.
According to Seth Berkley, president of the International Aids Vaccine Initiative, the "last two years have been the most exciting" because researchers have made the "biggest advances" in vaccines and preventions.
High on the list is work on broadly neutralizing antibodies, potent antibodies made by about 10-20 percent of people who are simply born with better natural defenses against HIV.
Scientists have now isolated 15 of these antibodies, and they are working backward to find ways to force the human immune system to produce them. When two are combined, they have been shown to block 90 percent of known HIV strains.
"The idea is if we could identify a strategy for the human host to be tricked into making broadly neutralizing antibodies, that is a huge step toward making a vaccine," said Myron Cohen, a leading AIDS researcher at the University of North Carolina at Chapel Hill. Cohen.
The use of drug therapy as a way to prevent HIV transmission has also gathered steam with a series of important clinical trials.
In early May, a global study of mainly heterosexual couples found a 96 percent lower risk of transmission to the uninfected person when antiretroviral therapy (ART) was started before the illness advanced in the sick partner.
In November 2010, a landmark study across four continents showed that a daily dose of an oral antiretroviral pill, Truvada, reduced the number of HIV infections among sexually active gay men by 44 percent.
The study focused mainly on men who have sex with men, and found that those who faithfully took the pill on 90 percent or more of days had a 73 percent lower infection rate.
However, hopes were dashed months later that the same treatment might work in HIV-negative women at high risk of exposure, when a trial of 2,000 women in Africa was stopped early because no benefit could be seen.
Trial operator Family Health International called the outcome "surprising and disappointing, given a number of earlier studies suggesting the promise of pre-exposure prophylaxis (PrEP) using antiretrovirals."
Analysis is ongoing to determine why the results were so different from the trial with gay men.
Meanwhile, targeting the tissues where transmission is most likely to occur has also been a promising area for researchers.
The use of antiretroviral gels applied vaginally or rectally have shown some positive effects toward prevention, and in 2006 a pair of trials in Africa showed that circumcised men were 48 and 53 percent less likely to become infected with HIV.
German researchers made headlines last year with the news that an AIDS patient who received a bone marrow transplant to combat his leukemia has remained virus free for three years, suggesting the first "cure" may have been achieved.
Even though the so-called Berlin patient underwent a radical operation that is too risky for most to survive, researchers are carefully examining his case for clues as to how to block HIV from entering the cells.
He received a transplant from a donor with a rare genetic mutation that is naturally resistant to HIV. About one in 100 Caucasian people, or one percent of the population, have the mutation, known as Delta 32, which prevents the protein CCR5 from appearing on the cell surface.
Since HIV enters the cell through CCR5 molecules, when they are absent HIV cannot penetrate.
While researchers say it will likely be another decade or two before a true cure may be found, they feel they are closing in on something big.
"When you put all those prevention models together and in combination, we are getting closer and closer to being able to say we may be able to turn this epidemic around," said Fauci.
earlier related report
This hope has been spurred by recent advances toward a vaccine and new breakthoughs in treatment and prevention, said Fauci who has headed the National Institute for Allergy and Infectious Diseases since 1984.
"Over the last one and half years we have had several important advances which when you put them together and combine them are now pointing very strongly to the fact that we can essentially be able to ultimately control and obviously ultimately end the AIDS pandemic," he told AFP.
Previous discoveries include how male circumcision can reduce by almost 65 percent the risk of transmitting the human immunodeficiency virus, the effectiveness of vaginal microbicides and drug treatments that can prevent an infected pregnant mother from passing the disease to her child.
More recently, two clinical trials have shown just how effective antiretroviral drugs can be in preventing the spread of the incurable disease.
A study that ran from 2007-2009 and was published late last year showed that a combination of these drugs taken orally by uninfected gay men lowered their risk by 44 percent of becoming infected.
That rate rose above 70 percent when the pills were taken regularly, said Fauci who added he has "been in it now literally every day of my life for the last 30 years."
A clinical trial released this month involving mainly heterosexual couples in which one was infected and one was not showed a near elimination of the risk of transmission when the infected partner began an early regimen of antiretrovirals.
This trial is "extremely important because it proves the concept that when you seek out and treat them early rather than wait for their disease to advance, you have not only the well known beneficial effect of being good for the individual patient, but you have a very powerful secondary effect of preventing the transmission from the infected partner to their healthy sexual partner," said Fauci.
The NIAID and its researchers have been at the forefront of the fight against AIDS since the epidemic first surfaced in June 1981.
With regard to the hunt for a reliable vaccine, researchers have found some hope after 20 years of failure in a 2009 clinical trial carried out in Thailand.
"The vaccine trial in Thailand was only 31% effective, however that is at least a proof of concept that we can do better."
In 2010, teams of researchers identified two antibodies in a single individual which when combined in the lab blocked 90 percent of HIV strains known in the world.
Now that research is honing in on what specific part of the virus should be isolated for a vaccine.
"So if we are going to have a vaccine this year or next year or the year after, we don't know, but we are certainly making considerable progress."
In the meantime, a more comprehensive use of existing methods for prevention must be applied in the developing world in order to put the brakes on the epidemic, Fauci said.
"In the low and middle income countries, we only have about 30 to 40 percent of the people who really need therapy getting access to therapy," he said.
"The only way we can address this -- and this is the focus of what is going on over the past couple of years -- is prevention of HIV infection."
There are 2.7 million new infections each year, he added.
This gap will be difficult to bridge, warned Fauci, especially since the global economic turndown has slashed research budgets as a time when scientists need 10 to 15 bilion dollars more per year than the total 11 billion currently available for research.
"Unfortunately there is a very difficult constraint on resources throughout the world," he said.
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The 30 Years War: AIDS, a tale of tragedy and hope
Paris (AFP) May 29, 2011
On June 5 1981, American epidemiologists reported a baffling event: five young gay men in Los Angeles, all previously healthy, had fallen ill with pneumonia. Two had died. They would be the first casualties of a new virus which has now claimed more lives than a world war. Nearly 30 million people have been killed by acquired immune deficiency syndrome (AIDS) and more than 33 million othe ... read more
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