An Australian research team has discovered a way of preventing HIV from spreading from cell to cell.Professor Henry and colleagues from the John Curtin School of Medical Research have found the drug hexamethylene amiloride (HMA) appears to reduce the ability of viruses to escape from infected cells. This could develop into a new drug to tackle HIV.
"We have found a drug that blocks the channels HIV may use to spread to uninfected cells," said Professor henry.Budding is the method by which viruses spread. After working their way into cells and making copies of themselves, the virus goes to the surface membrane and wraps it around themselves before 'popping' off.In 1996 the researchers showed that a protein created by HIV called Vpu formed ion channels in fatty membranes around cells. Ion channels act as 'gates' for ions to pass in and out of the cell."We had to make a conceptual leap between ion channels and the budding process" said Professor Gage who works in the Division of Biochemistry and Molecular Biology at the Australian National University. "We had an idea this would affect it but we didn't know how."
"The same part of Vpu is involved in making ion channels and budding, so the ion channels formed by Vpu could have a role to play in budding," said Professor Henry.Earlier this year the researchers showed that Vpu could dramatically increase the rate of budding. They concluded Vpu is likely to be important in viral reproduction."We found if we mess around with Vpu, we can reduce the rate of HIV replication in cells. Vpu isn't essential for replication, but it has an effect on it."
The researchers showed that the drug HMA stops the enhancement of budding by Vpu which indicates it will reduce the spread of the virus. "The virus will still replicate, but eventually the cell dies and the viruses, defenceless without surface membranes, are eaten up by macrophages," he explained.
At present there are two types of anti-HIV drugs available – reverse transcriptase inhibitors such as AZT and protease inhibitors. These work by targeting the reproduction of the virus within the host cell."The problem is HIV can mutate to escape the drugs you are using to treat it," said Professor Gage. "If this occurs, the drug will kill off all non-mutated cells leaving only the mutated ones to thrive." Any drug that results from this research will work with the current treatments. "This will complement existing anti-HIV therapies," said Professor henry. The advantage of multi-drug treatment is a reduction in the probability of a mutated virus escaping the treatment. The team has been working on the project for the past couple of years .
