Scientists in Sealed Lab Search for Bird-Flu Clues

In a sealed government lab where air rushes in but not out, two scientists in face masks and protective gowns have Hong Kong’s “bird flu” under the microscope.

Scientists who traded their holidays for a trip to Hong Kong to track the new H5N1 virus are back at the Centers for Disease Control and Prevention this week to continue the painstaking task of sorting through blood samples and virus specimens. They are trying to answer the most important questions about the virus that infected 18 people, killing six.

Did the virus pass from person to person? And why did the virus jump from poultry to people?

“These sound like simple questions, but to find scientifically sound answers may be difficult,” said Dr. Keiji Fukuda, who was the CDC’s chief flu investigator in Hong Kong. “It’s very unclear right now whether there are things which are peculiar about this particular virus or whether there are things about the people who got infected which makes them a little more susceptible to this virus.”

A wing of rooms used to study dangerous rickettsia bacteria at the CDC has been converted to the flu lab, where half a dozen scientists work hours at a time. Breaks, even for the bathroom, are impractical.

“You learn very fast not to drink a lot of coffee before you go into the lab,” said Henry Matthews, safety coordinator for the CDC’s National Center for Infectious Diseases.

The lab’s safety level is one notch below the maximum security room where scientists must don spacesuits to study Ebola, Lassa and other extremely deadly diseases for which there are no vaccines. Flu lab workers are offered an antiviral drug, rimantadine, as an extra precaution.

They pore over virus specimens and more than 3,000 blood samples from the flu victims, their relatives and others who had contact with them. A fax machine inside the lab lets the scientists send notes to their office without sending virus particles along.

In another lab, the CDC’s flu team is making a blueprint of the virus. This will help them come up with a virus that closely matches H5N1. That, in turn, could be used to make a vaccine.

One virus that closely matches the Hong Kong flu strain has been isolated from ducks in Singapore. It is being injected into ferrets.

The intensive lab work has taken longer than expected, but CDC scientists hope to release some findings later this month.

Here’s what they do know: Most of the Hong Kong flu victims were young--half of them under 10. Most did not live near chicken farms and all were from different corners of the city.

Another important clue is that the viruses from each sick person look the same, which suggests that most victims caught the virus directly from chickens. If the virus had spread from person to person, it would have mutated.

But why did the bird virus jump to humans?

Flu viruses are identified by two proteins on their surface called hemagglutinin and neuraminidase. There are 15 types of hemagglutinin, and birds have all of them. Historically, that’s why new flu strains often originate in birds. But usually they are passed to pigs first before infecting humans.

The Hong Kong outbreak was particularly frightening because it came at the start of flu season. Scientists feared the new H5N1 virus would mix with an old human flu virus and become capable of spreading quickly among people.