Animal Experiments Shed Light on HIV's Ability to Hide
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MONDAY, July 21, 2014 (HealthDay News) -- The "viral reservoir" in which HIV can lie dormant for years, avoiding detection and elimination, is established much earlier than previously thought, new animal research indicates.
This discovery poses new obstacles for those working to eradicate the AIDS-causing virus, said Harvard researchers working with the U.S. Military HIV Research Program. They said the presence of the viral reservoir remains the most significant challenge to finding a cure for a subtype of HIV, known as HIV-1.
"We found that the reservoir was established in tissues during the first few days of infection, before the virus was even detected in the blood," said the study's senior author, Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston.
For the study, published online July 20 in Nature, rhesus monkeys were infected intrarectally with simian immunodeficiency virus (SIV). SIV is believed to be the precursor of HIV in humans.
The researchers began antiretroviral therapy in groups of monkeys at three, seven, 10 and 14 days after they were infected with SIV.
Animals treated after three days showed no evidence of the virus in their blood and did not have an immune response to SIV. Despite six months of therapy, however, all of the animals had resurgence of the virus once treatment was stopped.
The investigators found that the earlier the treatment began, the longer it took for the virus to rebound, or become detectable in the blood. Still, the researchers concluded other strategies are needed to effectively cure HIV infection.
"The strikingly early seeding of the viral reservoir within the first few days of infection is sobering and presents new challenges to HIV-1 eradication efforts," the study authors wrote. The data suggest that extremely early initiation of [antiretroviral treatment], extended treatment and probably additional approaches that activate the viral reservoir will be required for HIV-1 eradication, they said.
The findings were reported in the wake of news that a Mississippi baby who was thought cured of HIV after receiving early antiretroviral therapy experienced a resurgence of the virus.
"The unfortunate news of the virus rebounding in this child further emphasizes the need to understand the early and refractory viral reservoir that is established very quickly following HIV infection in humans," added Barouch, a professor of medicine at Harvard Medical School in Boston, in a medical center news release.
Results of animal experiments aren't necessarily applicable to humans.
-- Mary Elizabeth Dallas
SOURCE: Beth Israel Deaconess Medical Center, news release, July 20, 2014