If you paid the slightest bit of attention to the news yesterday, you probably got word of reports proclaiming that doctors, for the first time, have figured out a way to cure an HIV positive infant.
While investigators cautioned that more follow-up research was necessary to understand the mechanisms behind this extraordinary case, I'm sure a good many people out there haven't fully wrapped their minds around how this is even possible.
So let's start with what we've been told. An account of the extraordinary case, detailed in a press release, emphasized the fact that a combination of drugs known as anti-retroviral therapy (ART) was administered very early, within 30 hours of the child's birth. The regimen, which the baby was put on for about 18 months, was then discontinued suddenly. Ten months after discontinuation of the treatment, the child underwent repeated standard blood tests, none of which detected HIV presence in the blood. Test for HIV-specific antibodies — the standard clinical indicator of HIV infection — also remained negative throughout.
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The medical team involved in the program, a collaboration between doctors from Johns Hopkins Children's Center, the University of Mississippi Medical Center and the University of Massachusetts Medical School, say the prompt administration of antiviral treatment likely led to the baby being cured, in part by halting the formation of hard-to-treat viral reservoirs — drug resistant dormant cells that reignite infection within weeks if the patients stops therapy.
Virologist Abbie Smith made an initial assessment of the reports and writes at ScienceBlogs that not only is this possible, it's also nothing new. Scientists have known for a while that right after being exposed to the virus, the "infected" person still has a short window in which anti-retroviral drugs can be exceptionally potent.
In every HIV lab there is a box on the wall with antiretrovirals in it. If you get exposed to the virus, you take the drugs, and you keep taking the drugs for, I believe, at least 6 months. The idea is, if we get exposed in the lab, we might have low levels of replication, but the drugs being RIGHT THERE immediately would keep us from getting genuinely infected. I know a couple people who have had to do this, and well, they aren't infected.
She explains, in slightly more technical terms, that during the very initial phase of transmission the virus is particularly vulnerable because the buildup of these drug resistant variants hasn't been established yet. In this sense, the doctors have called the event a "functional cure," wherein traces of viral DNA and RNA in the blood were present, though the virus was diminished to the point where it simply stopped replicating (remission).
The only recognized case of complete eradication of the virus, known as a "sterilizing cure," was of an HIV-positive man treated with a bone marrow transplant for leukemia. The bone marrow cells came from a donor with a rare genetic mutation of the white blood cells that renders some people resistant to HIV, a benefit that transferred to the recipient. This method of treatment, however, isn't considered feasible for the vast majority of people who are HIV positive.
A report on the case is scheduled for presentation at a press conference on Sunday, March 3, at the 20th Conference on Retroviruses and Opportunistic Infections (CROI) in Atlanta.
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