TUESDAY, SEPTEMBER 27, 2016

Scientists discover hiding place of HIV in human body

Scientists discovered a potential hiding place of HIV in the human body where the virus persists after antiviral treatment, according to a study recently published in Nature Medicine.

Researchers at Massachusetts General Hospital, the Ragon Institute of MGH, Harvard and MIT determined that the virus may hide in a small group of recently identified T cells with properties similar to stem cells. Since most human cells are short-lived, it was unclear how HIV managed to stay alive in the human body despite effective antiviral treatment.

"This question led to the hypothesis that HIV might infect stem cells -- the most long-lasting cells in the body -- but traditional organ-specific stem cells, even those that give rise to all immune and blood cells, are resistant to HIV infection," Mathias Lichterfeld, a corresponding author of the study, said. "We have discovered that a new group of T cells, called T memory stem cells, are susceptible to HIV and likely represent the longest lasting cellular niche for the virus."

HIV significantly impacts the human immune system because if infects CD4-positive T cells that usually direct and support infection-fighting activities of other immune cells. While most CD4 T cells are short-lived, CD4 T memory stem cells can live for decades. If CD4 T memory stem cells become infected, they can continuously regenerate new HIV-infected cells and keep the virus alive.

"Our findings suggest that novel, specific interventions will have to be designed to target HIV-infected T memory stem cells," Lichterfeld said. "Methods of inhibiting stem cell pathways are being studied to eliminate cancer stem cells -- persistent cells that are responsible for tumor recurrence after conventional treatments kill proliferating tumor cells. We are now investigating whether any of the drugs that target cancer stem cells might be effective against HIV-infected T memory stem cells."

Lichterfeld said the identification of reservoirs for HIV persistence represents an important step toward the development of interventions that induce long-term remission without the need for antivirals. He said that while the cure for HIV is elusive, it may not be impossible.