Scientist links 2 state outbreaks with genetic fingerprintsFree

SEATTLE — A U.S. scientist is helping public health authorities understand and track the coronavirus, turning up clues about how it arrived and spread through Washington state and beyond, including potentially seeding an outbreak on the Grand Princess cruise ship.

Like a detective studying fingerprints, Bedford uses the genetic code the virus leaves behind. The dots he connects are mutations in the genetic alphabet of the virus, a 30,000-letter string that changes at the rate of one letter every 15 days.

Those tiny mutations don’t change the virus’ effect on people, but they do allow scientists to draw conclusions about how it spreads from person to person.

After a person gets tested for the virus with nasal and throat swabs, a small bit of the specimen can be used to rapidly sequence the virus’ genome. That work has been happening, not just in Seattle, but in other labs around the world. Scientists are sharing their results on a public platform where they’ve been sharing influenza genome data since 2008.

This week, Bedford’s lab at the Fred Hutchinson Cancer Research Center worked with California researchers to find links between a cluster of cases in the Seattle area and the outbreak on the Grand Princess cruise ship in California.

“They all are very similar genetically,” Bedford told The Associated Press. “It seems very possible” that virus from the Washington outbreak made it onto the Grand Princess.

Dr. Charles Chiu at the University of California, San Francisco, agreed. He provided genome sequencing of seven samples from infected passengers who got off the Grand Princess this week. An eighth sample from an earlier Grand Princess cruise to Mexico had ties to Washington, Chiu said, and that person likely seeded the outbreak among passengers on board as the ship left for Hawaii.