The brain also acts as a key "reservoir" for HIV, scientists from Australia have found. This finding may be a serious threat to the search for a way to eradicate the virus from the body.
While scientists are using antiretroviral drugs to get rid of HIV altogether, they are finding it difficult to perfect techniques to kill off infected cells in the known reservoirs for HIV in the body.
Melbourne-based Dr. Melissa Churchill said that HIV was known to hide out in the thymus and lymph tissues, the gut, spleen, testes, bone marrow, they have recently found that it also resides in astrocyte cells in the brain.
"Previously, people weren't sure if we have to actually consider it as a genuine viral reservoir, but it is," she added.
Churchill and an international team of researchers used latest in high-powered microscopes to examine brain tissue from HIV-positive people to gauge the presence of the virus in these astrocyte cells.
She said that it was believed that the virus had about a "one per cent" presence, but the research showed it was up to 19 per cent and "very significant".
In her opinion, the discovery poses several new challenges for scientists now progressing the work of finding ways to eradicate HIV from the body.
"One of the issues of the brain as a reservoir is that it's quite inaccessible to the immune system and to anti-retrovirals," said Churchill.
It could also lead to brain damage.
"The cells that make up the other reservoirs, they can be regenerated - they are blood cells, things like that - but if you kill astrocytes, especially at this level, they don't regenerate. You lose the function that they normally carry out ... so you end up with a poorer (brain functioning) environment," she said.
In addition, it was believed that these infected and underperforming cells are also the cause of HIV-associated dementia, which commonly occurs in the later phases of HIV infection.