Experts Authenticate SARS Genetic Pattern

AP Science Writer

WASHINGTON – Two nearly identical sequences of the SARS virus genetic structure have been reviewed and authenticated by experts.

The publication of the virus genome, which is being rushed into print by Science journal, should help researchers find drugs to treat the deadly respiratory illness and to develop a vaccine to prevent the infection, experts said. Science is one of the world’s leading scientific journals.

A team of Canadians first sequenced a strain of the virus that causes severe acute respiratory syndrome, using specimens taken from a patient in Toronto, journal officials said Thursday.

Another form of the virus, called the Urbani strain, was sequenced shortly afterward by a U.S.-led team. The Urbani strain was earlier linked to a lung disease by Dutch researchers.

The sequences were posted on the Internet on April 15 but are only now being peer-reviewed, a scientific step that lends credence to the accuracy of the work.

Dr. Mark Pallansch of the Centers for Disease Control and Prevention, a member of the U.S. team, said the sequences prove that SARS is a type of coronavirus unlike any other in that viral family. Some vaccines have been developed for coronaviruses that attack animals, but SARS is so different, said Pallansch, “it is highly unlikely that we’ll be able to exploit any of the existing vaccines.”

And yet the genetic structure of the strain sequenced by the Canadian team and by the U.S. team are “extremely similar,” said Pallansch. Out of almost 30,000 nucleotides in the viral genetic structure, there was a difference between the strains in only 10 units, he said.

The most important applications of the sequences, he said, will be to refine diagnostics tests to enable doctors to quickly identify people infected with SARS.

The sequences were mapped on a crash basis by the two teams of researchers in an effort to distribute the data to other scientists and to drug companies as soon as possible, said Pallansch.

Science officials said the information is now freely available on the Internet for use by researchers worldwide.

“Both research teams produced these genomic sequences quickly and efficiently, in a model of cooperation among various groups,” said Don Kennedy, editor in chief of Science. “Because this information is crucial to the public health, Science is making it immediately available following an important and promptly conducted peer review.”

More than 5,400 cases of SARS have been diagnosed worldwide, with at least 375 deaths. In the United States, there are at least 53 probable cases, with more than 200 others considered suspicious but not yet officially tested. There have been no reported SARS deaths in the United States.

There are three groups of coronaviruses. Groups 1 and 2 are known to cause serious infections in animals. Viral strains in these groups also are responsible for about 30 percent of the mild upper respiratory infections in humans. Group 3 of the coronaviruses attack birds and can cause a serious bronchitis infection.

But Pallansch said the SARS is significantly different in genetic structure than all the known coronaviruses. This suggests SARS is of recent origin, but the researcher said it was not known how the virus developed. A number of viruses, including influenza, can be changed into a human pathogen by undergoing genetic rearrangement within other animal hosts.

Both of the sequencing studies have identified genetic pieces of the virus that may contain instructions for protein production, along with genes that enable the virus to infect cells and to reproduce, officials at Science said in a statement.

“These findings set the stage for further investigation into the viral proteins’ functions, possibly uncovering new targets for therapies or vaccines,” the journal said in a statement.