WASHINGTON — 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.
Copyright © 2013 AFP. All rights reserved. More »