Antiviral therapies have increasingly made HIV a treatable problem for those people who have access to medications. These therapies are so successful, in fact, that they can drive the virus back to the point where it becomes undetectable in blood samples. And yet—stop the treatment, and the viral load comes roaring back, meaning that it has a hiding place somewhere in the body. New research suggests that hiding place is the brain.
A thesis from the University of Gothenburg, Sweden finds that 10 percent of HIV-positive patients have traces of the virus in their spinal fluid, even when it is undetectable in their blood. Author Arvid Edén, researcher at the Institute of Biomedecine at the Sahlgrenska Academy, describes a study of 15 patients successfully treated for HIV for several years, 60 percent of whom had signs of the virus in their spinal fluid. "In another study of around 70 patients who had also received anti-HIV drugs, we found HIV in the spinal fluid of around 10% of the patients, even though the virus was not measurable in the blood, which is a significantly higher proportion than previously realised," Edén says.
Why would the brain guard the virus? "Antiviral treatment in the brain is complicated by a number of factors, partly because it is surrounded by a protective barrier that affects how well medicines get in," Edén explains. "This means that the brain can act as a reservoir where treatment of the virus may be less effective."
Even if current therapies are successful in holding the virus at bay, the goal is treatments that can eliminate it entirely. And, it is not clear whether the residual (albeit small) quantities of virus and inflammation in the brain and spinal fluid pose a health risk. "In my opinion," Edén says, "we need to take into account the effects in the brain when developing new drugs and treatment strategies for HIV infection."