hit virus

The key is finding the right target a gene and the protein it encodes, that the human cell doesn't need but the virus does. Human DNA contains more than 20,000 genes, but in any given cell at any given time, many are dormant : some, for instance, are only switched on during embryonic development. With the human genome now fully decoded, investigators can search for target systematically by disabling individual genes in many cells and seeing what happens. Zirus, a company in Buford, Georgia, uses a three step process (see opening illustration): it begin by infecting cells with a harmless retrovirus, which splices itself randomly into human DNA, knocking out any gene it interrupts. Other groups are disabling selected genes with matching bits of RNA. If the cell survives without a particular gene and is now resistant to infection, that gene protein combo is a promising target for a drug.

The first such drug. Pfizer's Maraviroc, is already being used to treat HIV infection ; it blocks a cell surface protein that acts as a receptor for the virus. San diego based nexbio has recently begun clinical trials of a compound called Fludase that inactivates the receptors through which both swine flu and seasonal flu enter respiratory cells. NIAID is vigorously supporting such research, "Over the next 20 to 30 years there will be a paradigm shift in the way we approach infectious diseases," Kurilla says. "I think this will be emblematic of 21st century medicine". -Josie Glausiusz,

to be continued ........