How does the swine flu virus work?

• Position: H1N1 - Brief article

Viruses are nasty--yet surprisingly simple--organisms. Most human flu viruses have 11 genes at most, compared to the more than 20,000 found in humans, point out researchers at the University of Texas Southwestern Medical Center, Dallas. What makes flu so potentially dangerous is that it is not very good at making copies of itself, which leads to mutations, or slight changes in its genetic code. Though most mutations do not amount to anything, some can lead to new versions--or strains--of the flu that could spread more easily or make people sicker once infected.

"H1N1 is very different from the normal seasonal flu, especially in parts of the virus normally recognized by our protective immune system," indicates Richard Scheurmann, professor of pathology who also is principal investigator of the National Institutes of Health-funded Influenza Research Database. "H1N1 has not mutated in such a way as to make people sicker, but it...