Researchers have discovered that astrocytes, a type of brain cell, can harbor HIV and spread the virus to immune cells that traffic out of the brain and into other organs. HIV moved from the brain via this route even when the virus was suppressed by combination antiretroviral therapy (cART), a standard treatment for HIV, according to a National Institutes of Health (NIH) press release.

“This study demonstrates the critical role of the brain as a reservoir of HIV that is capable of re-infecting the peripheral organs with the virus,” said study co-funder Jeymohan Joseph, PhD, chief of the HIV Neuropathogenesis, Genetics, and Therapeutics Branch at NIH’s National Institute of Mental Health, in the press release. “The findings suggest that in order to eradicate HIV from the body, cure strategies must address the role of the central nervous system.”

cART has helped many people with HIV live longer and effectively suppresses HIV infections, according to the press release. However, some studies have shown that many patients receiving antiretroviral drugs have shown signs of HIV-associated neurocognitive disorders, such as thinking and memory problems.

Although researchers know that HIV enters the brain within 8 days of infection, less is known about whether HIV-infected brain cells can release the virus, letting it migrate from the brain back into the body to infect other tissues.  

Astrocytes can perform a variety of tasks in the brain, such as supporting communication between brain cells to maintain the blood-brain barrier, according to the press release. To further analyze whether HIV can move from the brain to peripheral organs, researchers transplanted HIV-infected or noninfected human astrocytes into the brain of immunodeficient mice.

The study found that the transplanted HIV-infected astrocytes were able to spread the virus to CD4-positive T cells in the brain. The CD4-positive T cells migrated out of the brain and into the rest of the body, spreading the infection to peripheral organs, such as the spleen and lymph nodes.

Further, the researchers found that HIV egress from the brain occurred, albeit at lower levels, when animals were given cART. When cART treatment was interrupted, HIV DNA/RNA became detectable in the spleen, indicating a rebound of the viral infection.

The results have significant implications for HIV cure strategies, such as the need to be able to effectively target and eliminate reservoirs of HIV replication and reinfection, according to the press release.

Brain cells can harbor and spread HIV virus to the body. NIH. Published June 11, 2020. Accessed June 24, 2020.