After 15 years of futile search for a vaccine against the AIDS virus, researchers are reporting the tantalizing discovery of antibodies that can prevent the virus from multiplying in the body and producing severe disease.
They do not have a vaccine yet, but they may well have a road map toward the production of one.
A team headquartered at the Scripps Research Institute in San Diego reports today in the journal Science that they have isolated two so-called broadly neutralizing antibodies that can block the action of many different strains of HIV, the virus responsible for the AIDS pandemic.
Crucial to the discovery is the fact that the antibodies target a portion of HIV that researchers had not previously considered in their search for a vaccine. Moreover, the target is a relatively stable portion of the virus that does not participate in the extensive mutations that have made HIV able to escape from antiviral drugs and previous experimental vaccines.
"This is opening up a whole new area of science," said Dr. Seth Berkley, president and chief executive of the International AIDS Vaccine Initiative, which funded and coordinated the research.
At least 33 million people worldwide are currently infected with HIV and at least 25 million have died from AIDS, according to the World Health Organization. Two large trials of experimental vaccines have failed, the most recent, in 2007, because the vaccine apparently made people more susceptible to infection.
To find the neutralizing antibodies, researchers went to Thailand, Australia and Africa, collecting blood samples from more than 1,800 people who had been infected with HIV for at least three years without the infection proceeding to severe disease. Such individuals are most likely to produce antibodies that interfere with the replication of the virus.
Researchers at Monogram Biosciences Inc. in South San Francisco then studied the samples most resistant to infection. A team from Theraclone Sciences in Seattle then isolated the antibodies responsible for the resistance.