Sars breakthrough

2003-04-13 14:36

Vancouver - Scientists here on Saturday broke the genetic code of the virus suspected of causing Sudden Acute Respiratory Syndrome, the first step toward developing a test for doctors to diagnose victims of Sars or, in future, a possible vaccine.

Currently, doctors worldwide diagnose Sars patients by a combination of unusual symptoms, including very high fever, difficulty breathing, a dry cough and contact with someone else suspected of having Sars.

Because of the lack of a definitive test, the Sars diagnosis is currently labelled by doctors as either "probable" or "suspect."

The genetic code is the raw material needed by scientists trying to develop a diagnostic test, said Doctor Marco Marra, director of the Michael Smith Genome Sciences Centre, which is part of the British Columbia Cancer Agency.

"One could use these portions of the viral genome to test patients for infection by the virus," said Marra.

Since Sars first appeared last November in China and began to spread internationally through travellers early this year, the disease is suspected of infecting nearly 3 200 people worldwide and causing over 125 deaths.

Doctors baffled

Until now doctors have focused on trying to control the infection from spreading, by screening airports and placing people with possible cases in hospital isolation units and those with suspected cases in quarantine.

The disease has baffled doctors because Sars symptoms were so unusual and the death rate relatively high.

Patients often started out with flu-like symptoms, which were followed by a pneumonia that prevented them from breathing and, in the worst cases, caused their lungs to fill with fluid. There is no cure to date.

This week scientists in several centres reported that Sars is most likely caused by a virulent new coronavirus, the type of virus that causes influenza, and laboratory researchers around the world raced to break its genetic code.

The genetic sequence was posted on the internet (www.bcgsc.bc.ca) for use by other scientists around the world immediately after it was broken early on Saturday, and later was released to the public by the Genome Sciences Centre.

The genome-sequencing laboratory in this west coast city is normally dedicated to cancer research, but came on board with Canada's National Microbiology Lab in Winnipeg, Manitoba and the BC Centre for Disease Control to help with the global fight against Sars.

The new information, said Marra, "Will tell us if Sars resembles other viral genomes, and gives us hints about the biology of the virus."

"We anticipate there will be additional outbreaks," said Marra. "It's important for us to learn the lessons from this experience, to prepare ourselves for the future."

Canada reported on Saturday three more deaths linked to Sars, bringing the nationwide toll to 13. The majority of the 274 suspected cases have occurred in the province of Ontario, where the first Sars case was reported in Canada.

- AFX