Genetic Code of Common Cold Cracked

Feb. 12 -- THURSDAY, Feb. 12 (HealthDay News) -- Today's medical breakthrough: a cure for the common cold.

Well, researchers are reporting what could at least be a significant step in that direction: the genetic codes of the 99 known viruses responsible for those pesky nasal infections.

"There has been brilliant work done trying to synthesize compounds against the common cold," said Dr. Stephen B. Liggett, director of the cardiopulmonary genomics program at the University of Maryland, and senior author of a report on the discoveries published in the Feb. 12 online issue of Science. "But we have not been working with a full knowledge of the genetics of rhinoviruses. Now that we have the full complement of known ones, we see there are subfamilies of rhinoviruses clustering together. The hope is that there could be a drug for each subfamily."

Liggett and the other researchers in the project used virus samples collected by nasal swabs in doctors' offices over two decades and sent to the American Type Culture Collection, a private nonprofit organization headquartered in Virginia. Some rhinovirus genomes had already been sequenced from those samples. The current study adds 80 new full genome sequences, showing their relationships.

"We made a family tree," Liggett said. "The major branches are going to be fixed. We have sequenced rhinoviruses from 10,000 individuals at different locations in the United States, and we see major branches in the trees, with lots of little twigs in the tree."

The viruses are still evolving, Liggett said. "We compared some samples taken in 2005 with some from the 1970s, and found a fair number of mutations," he said. "But the major evolutionary structure of the tree is not going to change."

Rhinoviruses can't change too much, Liggett explained. "If they mutate to become super virulent, they destroy the cells they live in. They might become less deadly and narrow down the window they operate in. We don't understand that window very well."