STUDY: Monkeys Treated With Antibodies Cleared of HIV
Here’s another “WOOT!” for the power of antibodies in fighting HIV.
Research published this week in Nature Medicine showed that when infant monkeys were given antibodies within 24 hours of being exposed to SHIV, or monkey HIV, they completely cleared the virus.
“We knew going into this study that HIV infection spreads very quickly in human infants during mother-to-child transmission,” said Nancy L. Haigwood, senior author of the paper, in a news release. Haigwood is director and senior scientist at Oregon National Primate Research Center at Oregon Health & Science University.
“So we knew that we had to treat the infant rhesus macaques quickly but we were not convinced an antibody treatment could completely clear the virus after exposure,” Haigwood continued. “We were delighted to see the result.”
In the U.S., mother-to-child HIV transmission has been slashed from 25 percent to less than 2 percent since 1994. In humans, mothers and infants are treated with antiretroviral therapy, babies are delivered by Cesarean section, and they are nursed with formula instead of breast milk to prevent HIV infection. But approximately 200,000 babies per year still are born with HIV every year, especially in countries where ART is not available.
For the study, the monoclonal antibodies were given subcutaneously (injection under the skin) on days 1, 4, 7 and 10 after the macaques were exposed to HIV orally. “Early short-term administration of powerful antibodies effectively cleared the virus by day 14, with no virus detected at this time,” according to the news release. “Using highly sensitive methods, they did not detect the virus in any part of the body in 100 percent of the antibody-treated macaques for at least six months.”
The study showed that antibodies delivered subcutaneously “are swiftly distributed to blood and tissues and maintain neutralizing activity at various sites” and “antibodies are effective at clearing the virus, a different mechanism than that of ART, which is a combination of several antiretroviral medicines used to slow the rate at which HIV makes copies of itself in the body.”
According to the research abstract, “Replicating virus was found in multiple tissues by day 1 in animals that were not treated. All NmAb-treated macaques were free of virus in blood and tissues at 6 months after exposure. We detected no anti-SHIV T cell responses in blood or tissues at necropsy, and no virus emerged after CD8+ T cell depletion. These results suggest that early passive immunotherapy can eliminate early viral foci and thereby prevent the establishment of viral reservoirs.”
Clinical trials among HIV-exposed newborns treated with antibodies have begun in the U.S. and South Africa following a phase I trial in HIV-negative adults that showed the antibodies are safe and well tolerated.