By Wilson da Silva
SYDNEY – Australian scientists said on Wednesday they had cloned and genetically mapped a molecule which French researchers only days ago identified as the key that allows the AIDS virus to enter human cells.
They said the next step, a close study of the molecule’s genetic structure, could uncover a weakness that would open the door to developing drugs capable of halting the AIDS virus from invading healthy human cells.
Associate Professor Geoff McCaughan of Sydney’s Royal Prince Alfred Hospital told Reuters that his team had just completed what he believes is the first complete mapping of the genetic structure of the co-receptor molecule, known as CD26.
The Australian researchers said they would be providing the genetic map of CD26 to AIDS scientists.
Scientists at France’s Pasteur Institute announced on Monday they had identified the molecule CD26 which works along with the known receptor CD4 to allow the AIDS-causing Human Immunodeficiency Virus (HIV) virus to infect cells.
The Australian scientists had known of the existence of CD26 for five years but were not aware of its importance to AIDS research until Monday’s announcement.
“We’ve just completed a sequencing to find out the exact genetic structure of the molecule,” said McCaughan, whose team has been studying the molecule’s relationship with liver disease.
Following the French discovery, the Australians are now trying to match differences they had found in the molecule’s genetic structure with how the virus affects those infected with the Acquired Immune Deficiency Syndrome (AIDS).
McCaughan said the variations might account for why some people develop the disease shortly after infection, some take years, and others appear to remain immune.
If CD26 is the key to how HIV infects human cells, as the French researchers suggest, the genetic map may allow scientists “to target these as a way of reducing the number of CD26 molecules expressed, thereby reducing the risk of HIV infection,” McCaughan said.
While CD4 allows HIV to hook on to cells, CD26, also known as dipeptidyl peptidase IV, serves as a door allowing the virus to penetrate the cell.
French scientists said that if the discovery holds true, experts could use genetic manipulation to place the CD4 and CD26 receptors in laboratory mice, thus creating the long- awaited animal model AIDS researchers so urgently need.
The director of the virology department at Sydney’s Westmead Hospital, Associate Professor Tony Cunningham, said scientists had been “chasing the ‘holy grail’ of the second receptor on cell surfaces.”
“The more you find about how those keys fit into the lock, the more you can find out how to produce antiviral agents that may interfere with entry and how to boost the immune response against both those keys,” he told reporters.