The famous infant born with HIV (human immunodeficiency virus) and given antiretroviral medicine 30 hours after birth now shows detectable levels of the virus in his or her bloodstream. The infant, known as the “Mississippi Baby,” astounded doctors by staying in remission for more than four years.
When the child’s mother, who was HIV-positive but not taking antiretroviral medicine, first gave birth doctors administered medicine to the baby. After several days, doctors confirmed the virus’s presence. The child began liquid, triple-drug therapy. But after nearly two years, clinical follow-up showed undetectable HIV levels (less than 20 copies of HIV per milliliter of blood). The latest tests, administered as part of a routine exam, showed the levels at 16,750 copies/mL.
The initial prognosis seemed good. Plus, no more than a year after the Mississippi Baby’s two-year follow-up, a second baby was born in Los Angeles with similar results. Quick, hard treatment was working. Before the virus had a chance to replicate, doctors were cutting its legs out from under it. HIV is potent because it encodes its genome backward, making early detection difficult. Doctors decided to strike first and stop that encoding from happening.
An absence of retroviral therapy appears to have run its course, however. "Certainly, this is a disappointing turn of events for this young child, the medical staff involved in the child's care, and the HIV/AIDS research community," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, in a statement.
In addition to the massive viral presence in the toddler’s blood, doctors also discovered a decrease in CD4+ T-cells, active components in a well-oiled immune system. They found HIV antibodies — a surefire sign that the virus was replicating unabated. And as expected, when doctors performed genetic sequencing of the child’s blood, the virus turned out to be the same strain as the mother’s. After four years, retroviral therapy has now resumed.
The big question that emerges from all this, of course, is: What happened? What kept the virus dormant for so long, and what made it reappear out of the blue?
"The fact that this child was able to remain off antiretroviral treatment for two years and maintain quiescent virus for that length of time is unprecedented," said Dr. Deborah Persaud, professor of infectious diseases at the John Hopkins Children's Center in Baltimore. Persaud has observed the case since its inception. She says the timeframe for HIV’s reemergence is far longer than she would have expected. "Typically, when treatment is stopped, HIV levels rebound within weeks, not years."
Researchers speculate that something had to be going on with the child’s cells for its body to harbor the virus for so long, but without manifesting an immune response. At any rate, researchers now know that antiretroviral therapy right after birth isn’t as foolproof as once believed. While the medicine may eradicate the virus for a short or even moderate amount of time, it isn’t all-encompassing.
In addition to the ongoing mystery of how to get rid of HIV in newborns, the case offers up a second mystery to be solved, namely: Why is antiretroviral medicine effective at functionally curing the virus, but only for a certain period of time? Researchers have spent decades trying to solve how HIV arises in the first place — the first mystery. "Now,” Fauci said, “we must direct our attention to understanding why that is and determining whether the period of sustained remission in the absence of therapy can be prolonged even further."