Methamphetamine drastically increases HIV-like virus's ability to replicate in the brain

Brain cells infected with the feline version of HIV (FIV) permit the virus to replicate at a massively increased rate when exposed to the recreational drug methamphetamine, according to a US study published in the June 2002 edition of the Journal of NeuroVirology.

Researchers at Ohio State University found that two weeks exposure to methamphetamine at a level equal to that normally found in an adult user’s blood stream, increased HIV replication in infected cells as much as 15-fold.

Although the research was conducted on cat cells infected with FIV, the research has potentially significant implications for understanding how HIV (which like FIV is a lentivirus), infects brain cells.

In particular, the Ohio State researchers looked at the role of astrocytes, nerve cells in the brain, which play an important part in immunity. It had been believed that FIV and HIV infection of astrocytes was latent, with the virus remaining dormant and causing few problems.

It was established that FIV can only enter astrocytes when they are associated with a peripheral blood mononuclear cell. A receptor molecule on the astrocytes outer membrane (CXCR4) allows both FIV and HIV to enter the cell.

Once the astrocyte had been infected, the virus rapidly reproduced, mutating into a different strain, completely independent of any immune system interaction, leading the American researchers to speculate that treatments intended to enhance the immune system's ability to control the virus could have absolutely no impact on the infected astrocytes in the brain.

Although HIV-related brain disorders such as dementia and mania, are rarely seen in HIV patients thanks to the success of HAART, the brain remains a reservoir of HIV infection and only a limited array of the currently available anti-HIV drugs are able to suppress HIV replication in the brain.

This is the second study this year using animals that has suggested that recreational drugs can increase HIV replication. Earlier this year, a study found that mice infected with HIV and exposed to cocaine displayed faster disease progression. Methamphetamine is a stimulant drug which is particularly popular amongst gay men, notably in the USA and Australia.