In a sobering discovery, researchers say that rapid treatment of HIV-like infections in monkeys failed to prevent the establishment of persistent viral reservoirs in as little as three days.
The study, published Sunday in the journal Nature, comes on the heels of news that the so-called Mississippi Baby -- a child once considered functionally cured of HIV due to antiretroviral drug treatment hours after her birth -- had in fact been infected with the virus all along.
While researchers had begun to hope that there was a window in which the virus could be prevented from establishing a permanent foothold within its host, that possibility now seems much less likely.
"We show that the viral reservoir can be seeded substantially earlier than previously recognized," wrote lead study author and Harvard Medical School virologist James Whitney, and colleagues.
HIV attacks CD4 white blood cells -- critical components of the body's immune system. The virus then uses the cells to manufacture copies of itself, destroying the blood cell in the process and steadily eroding the body's internal defenses.
However, in some cases, the virus will lay dormant within a white blood cell, only to begin reproducing itself at a later date. The virus cannot be killed in this dormant state -- either by the body's immune system or by antiretroviral drugs -- and this latent reservoir of infection has proved to be the biggest obstacle to finding a cure.
In the latest study, researchers infected 20 adult rhesus monkeys with simian immunodeficiency virus, or SIV, the simian equivalent of HIV, the disease that causes AIDS.
Some of the monkeys were treated with a cocktail of antiretroviral drugs three days after infection, yet prior to when the virus could be detected in the monkeys' bloodstream. Other monkeys received the drug treatment at seven, 10 and 14 days after infection, when evidence of the illness could be detected.
In each case, antiretroviral therapy was stopped after 24 weeks. While researchers had hoped the virus would not reappear in the monkeys that were treated in three days, it in fact rebounded in all of the animals.
The researchers, however, did note that it took about three weeks for the virus to rebound in the monkeys that received drug treatment after three days, where it took only one or two weeks in the other monkeys.
In an accompanying News & Views article, Kai Deng and Dr. Robert Siliciano, both HIV researchers at Johns Hopkins University Medical School, noted that further research was needed to confirm the study's results.
"Substantial differences exist between SIV infection in rhesus macaques and HIV-1 infection in humans," the pair wrote.
Nonetheless, they called the paper's findings "striking," as they argued that still newer medical approaches are needed to eradicate HIV.
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