Researchers discover SARS' genetic blueprint

Researchers in Canada and the US have reported success in isolating and mapping a likely culprit for the recent outbreak of SARS (severe acute respiratory syndrome).

British Columbia-based Michael Smith Genome Sciences Centre says it has generated the genetic sequence of the Toronto isolate, TOR2, of the coronavirus associated with SARS. A similar report in the New England Journal of Medicine detailed CDC identification of a 300-nucleotide sequence using a PCR-based random-amplification procedure.

However, it seems researchers are still yet to be convinced as to the exact nature of SARS, with the WHO putting forward three possible scenarios. The first and most popular is the coronavirus theory, the second is that a paramyxovirus is the cause, with the third approach assuming a combination of the two viruses.

Australian virologist Bryan Eaton agreed the mapping was a major step forward in combating the current epidemic.

"These results should help us to get a useful test for SARS," said Eaton, senior principal research scientist at the Australian Animal Health Laboratories.

"The next step is to come up with two tests for SARS. The first would be to identify the virus at the nucleic acid level, and then as soon as possible we need to work out a second, antibody test."

As yet, it seems the virus is only distantly related to known coronaviruses, but on the basis of the obtained sequences, conventional and real-time PCR assays for specific detection of novel virus have been established.

Eaton noted the antibody test would be extremely useful in tracking down possible wild animal sources, and also in determining exactly where the virus had come from.

"Australian labs are looking at getting the virus in to work on it. They will probably be looking at where it could go next, and in what animals it can travel. We are hoping it is a single virus -- if not things could get extremely tricky. However, it does appear to be a single virus so far -- enough labs have come up with similar results to make this likely," he said.

At time of press, SARS had been identified in 2960 cases, with 119 deaths worldwide.