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Scientists Crack SARS' Genetic Code

<P>Achievement Should Lead to Better Testing and Treatment</P>

WebMD Health News

April 14, 2003 -- Barely one month after research into an outbreak of a mysterious new respiratory illness began, scientists in Canada and the U.S. have created a detailed genetic map of the virus widely believed to cause SARS (severe acute respiratory syndrome). After working night and day for weeks, Canadian scientists announced this weekend they had completed full genetic sequencing of the coronavirus linked to SARS, and CDC officials followed suit today with a similar announcement.

"Sequencing the virus is a major scientific achievement, and the fact that it was done so fast is unprecedented in history," said CDC director Julie Gerberding, MD, in a briefing today. "But it is not a magic bullet for dealing with SARS."

Gerberding says the genetic sequencing of the previously unknown coronavirus is a necessary step for developing accurate tests to screen for SARS as well as creating an antiviral vaccine to treat and prevent SARS. But she cautions that due to the extensive testing required it would be naïve to think that a commercially available, licensed vaccine would be available in less than a year.

Researchers say the rapid sequencing of the virus was facilitated by the unparalleled international cooperation of a network of laboratories and scientists assembled last month by the World Health Organization (WHO).

"It's tremendously exciting that 31 days into this that we've not only identified the likely cause of SARS, but have also sequenced the virus and created a number of promising diagnostic tests," says Gerberding.

A new molecular test based on genetic information that was developed at the CDC has been shown to be up to 10 times more sensitive at identifying SARS than previous diagnostic tests. The test has proven effective in picking up tiny portions of the SARS-related coronavirus present in small concentrations in samples taken from infected patients.

WHO officials say they hope to have the CDC test available for international use by the end of the week, but Gerberding says getting a fully licensed test ready for widespread use will likely take several weeks.

Despite these promising developments in SARS research, officials say they are concerned about the continued spread of the disease. More than 100 new SARS cases and six deaths were reported over the weekend in China. SARS cases are now being reported in growing numbers in Shanxi province, as well as Mongolia and Fujian, which indicates the disease has not yet been contained in China.

Last week, WHO officials expressed concern over whether rural Chinese provinces would be able to respond effectively to SARS. Since the outbreak of an unusual pneumonia began in China last November, 1,418 cases and 64 deaths have been linked to SARS in that country. Worldwide, there have been 3,169 cases and 144 deaths.

WHO officials say the focus of scientific research on SARS is now determining what's unique about the roughly 4% of SARS patients who die of the disease. Three of the deaths reported over the weekend in Hong Kong were among people under 50, which makes a departure from previous patterns in which SARS deaths were primarily among the elderly or those with preexisting illnesses.

Gerberding says 193 suspected SARS cases are currently under investigation in the U.S., but that number is expected to drop later this week as the CDC adopts a stricter definition of "probable" rather than "suspected" SARS cases, which is in line with WHO standards.

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