Scientists from Australia and Britain have discovered a new method which may help to target the HIV virus as it makes its way to infecting cells.

Scientists from the University of New South Wales (UNSW) in Australia, led by Associate professor Till Bocking, described on Tuesday how the HIV virus forms a protein shell called a capsid, to protect itself from the hosts defence mechanism as it infects the nucleus of a cell.

Using a new microscope technique developed at UNSW, the team discovered that the HIV virus uses a molecule from the host cell to strengthen its capsid.

"It's like a switch, when you bind this molecule, you stabilize the capsid, and release the molecule to open it up," Bocking said.

The molecule, called inositol hexakisphosphate, is abundantly present in mammals and has been seen to make the HIV capsid much stronger, stabilising it for 10 to 20 hours.

Because the infection process takes hours, it was crucial for scientists to find out how the virus was keeping stable within the cell.

"The HIV capsid has been intensively studied," leader of the British research team at Cambridge, Dr Leo James said.

"But the question of how it can simultaneously be both stable and poised to 'uncoat' has been one of the great unanswered questions in HIV biology."

To assist in their study, the team engineered viruses with fluorescent tags to monitor the viral capsid using fluorescence microscopy.

"We can now see the effect of different molecules on the capsid, and pinpoint precisely when it cracks open and begins to collapse," Bocking said.

In the team's findings, they identify a new target for antiviral therapy against HIV and provide a method for testing and measuring new drugs designed to target the capsid.

While there currently no HIV therapies targeted at the HIV capsid, it is hoped that new therapies could improve treatment with reduced toxic effects.