HIV Hides In Bone Marrow

Researchers have learned that HIV can lie dormant for years in bone marrow, evading drug therapy and later activating to cause disease. The issue of "hidden" HIV has been one of the biggest obstacles to attempts to completely clear the virus from the body.

Dr. Kathleen Collins of the University of Michigan and her colleagues report in this week's edition of the journal Nature Medicine that the HIV virus can infect long-lived bone marrow cells that eventually convert into blood cells. The virus is dormant in the bone marrow cells, she said, but when those progenitor cells develop into blood cells, it can be reactivated and cause renewed infection. The virus kills the new blood cells and then moves on to infect other cells, said. "If we're ever going to be able to find a way to get rid of the cells, the first step is to understand" where a latent infection can continue, Collins said.

In recent years, drugs have reduced AIDS deaths sharply, but patients need to keep taking the medicines for life or the infection comes back, she said. That's an indication that while the drugs battle the active virus, some of the disease remains hidden away to flare up once the therapy is stopped. One hide-out was found earlier in blood cells called macrophages. Another pool was discovered in memory T-cells, and research began on attacking those. But those couldn't account for all the HIV virus still circulating, Collins said, showing there were more locations to check out and leading her to study the blood cell progenitors.

Depressing news perhaps, but at least scientists have one more target in the quest to get people to the point where they can cease medication.