Infect a small study group with rhinovirus-16, the source of the common cold. Scrape cells from inside their noses; repeat for a control group that got a sham inoculation. Then use gene-chip technology to see how more than 6,000 of the symptom sufferers’ genes express themselves.

…[R]hinovirus infection triggered a massive immune response in the nasal mucosa. Because rhinovirus is not as destructive as other more serious viral infections, this response appears to be disproportionate to the threat…. “This study shows that after rhinovirus infection, cold symptoms develop because parts of our immune system are in overdrive,” said Lynn Jump, principal researcher at Procter & Gamble and study author. “The findings are important because they provide us a blueprint for developing the ideal cold treatment: one that maintains the body’s natural antiviral response while normalizing the inflammatory response.”

An antiviral compound called viperin, produced by the epithelial cells, seems to fight the influenza virus, too.

[Rhinovirus: actual microscopic image! by hey mr glen]