HIV infection mystery revealed

By Dr. Ananya Mandal, MDSep 22 2010

In a new discovery, Melbourne researchers have found a mechanism by which the HIV virus can affect people. According to co-head of the Burnet Institute's Centre for Virology, Sharon Lewin, scientists have found out how HIV entered a group of cells in which the virus tends to persist in spite of antiviral treatment that reduces the virus to undetectable levels.

She explained that these “resting cells” have been a barrier in the search for a cure because the virus seemed to hide in the cells and resurface when people stopped treatment. She said, “'This is the first time we've identified how HIV gets into these resting cells…That's important because when people are on treatment, it doesn't target the virus in these cells … so whenever you stop treatment, the virus comes straight back up again within two or three weeks…One of the major reasons why that happens is because the virus hides in these resting cells.”

She also said that this discovery could mean newer avenues in anti HIV drug research. “'It's a really good model for screening new drugs that could get rid of these infected resting cells so I imagine other investigators and pharmaceutical companies will be very interested in it,” she said.

“Our team of researchers has now identified the path by which the virus can infect resting CD4-T cells and establish latency…We have shown that a family of proteins, called chemokines, that guide resting cells through the blood and into lymph node tissue can “unlock the door” and allow HIV to enter and set up a silent or ‘latent’ infection,” Professor Lewis explained.

The director of the Burnet Institute, Professor Brendan Crabb also enthused at these findings saying, “We've been working on the virus for 30 years and it's really only now that we're beginning to see that a cure for HIV might be achievable and needs to be a major scientific priority.”

Professor Lewis, who is also director of the Alfred's infectious diseases unit revealed that this finding was chanced upon when she was preparing to trial a new drug on patients that could push the virus out of resting cells.

“Understanding this mechanism will enable new treatment options to be developed which could block latent infection. This new laboratory model of latent HIV infection can also be used to screen drugs that may one day eliminate latent infection,” co-author and Monash clinical immunologist Dr Paul Cameron said.

The research was published in the Proceedings of the National Academy of Science this week and involved scientists from Burnet, Melbourne's Alfred hospital, Monash University, University of Montreal, Canada and the Westmead Millennium Research Institute in Sydney.

The number of HIV diagnoses in Australia increased by 38 per cent from 718 in 1999 to 995 in 2008. In 2008 about 17,000 Australians were living with HIV.