U.S. and Canadian researchers have shed some light on the virus that causes Severe Acute Respiratory Syndrome, or SARS. Scientists say the additional information should aid in the development of a treatment and vaccine to fight the pneumonia-like illness.
Researchers have come up with the entire genetic sequence of two strains of the SARS virus.
Worldwide, nearly 5,700 people have come down with the previously unknown illness and at least 370 have died.
The studies describing the molecular structure of the two strains are being published in the journal Science.
SARS originated in China, where it is taking its biggest toll. Scientists are actively working to find out whether the illness there is caused by yet another viral strain.
Researchers say their work provides some clues as to how the virus enters cells. They hope this will speed the development of screening tests, drugs and vaccines to fight SARS.
But Mark Pallansch of the U.S. Centers for Disease Control and Prevention in Atlanta, Georgia, says the difference in viral strains could make vaccine development more challenging.
"It's too early to know whether these differences would have an effect that would make vaccine development more or less difficult; whether it would be something like influenza, where the vaccine would have to be changed on a routine basis, or something like polio virus, where the same vaccine is used for nearly 50 years," he said.
Scientists say the SARS virus started in animals and jumped to humans. But they say it is highly unlikely vaccines used successfully to treat the animal version of the disease will work in people.
Researchers also confirmed that the microbe is not a mutation of other so-called corona viruses that cause the common cold and other respiratory illness, but rather a new variety.