National Geographic : 2010 Jan
1 RETROVIRUS LIVING CELL GENE DYING CELL ART BY BRYAN CHRISTIE REPORTING BY FARHANA HOSSAIN SOURCES: ZIRUS; NATIONAL INSTITUTES OF HEALTH; HARVARD MEDICAL SCHOOL Viruses that infect us can't spread without us. Finding their helpers inside human cells may yield drugs that stop pandemics. Hit Them Where They Live 1 WITHIN A FEW MONTHS of the outbreak of swine flu last spring, public health officials reported the first cases resistant to Tamiflu. It was no surprise. The previous winter most cases of seasonal flu had also proved resistant to the drug. Why don't we have antivirals as good as antibiotics are against bacteria? Viruses are wilier; they mutate so fast that they slink from the grasp of even the best designed drugs. But researchers are now working on a radical new strategy that just might help ward off future pandemics and produce the antiviral equivalent of amoxicillin. The idea is simple: Instead of attacking viruses directly, target the human cells they infect. Bacteria are organisms that are equipped to reproduce themselves; antibiotics attack that machinery. But a virus is a parasite: It invades a host cell and co-opts the cell's own machin- ery to make copies of itself---thousands of copies at once, which means thousands of chances to mutate and develop drug resistance. A drug that disables a part of (Continued on next page) THE BIG IDEA | PANDEMIC CONTROL FIND UNNEEDED GENES A harmless retrovirus (red) is used to knock out a different gene (green) in each human cell of a colony. If a cell survives, that means the targeted gene wasn't producing an essential protein. To find new targets for antiviral drugs, scientists look for genes that human cells don't need but viruses do. One search method is shown here.