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Posted on 04/16/2003 9:08:53 AM PDT by Dog Gone

A NEW genetic sequencing of the SARS virus proved conclusively that it came from animals - answering a question that had been left hanging following earlier such tests in North America - researchers in Hong Kong said today.

The University of Hong Kong researchers also said they believe - but have not proven - that the virus mutated into a more dangerous form that infected about 300 people in one hard-hit apartment complex in the city.

"This virus did not originally exist in humans, it definitely comes from animals," said Yuen Kwok-yung, a microbiologist at the University of Hong Kong.

But scientists from the university told a news conference that more research is needed before they can hope to know which animal species had spread severe acute respiratory syndrome to humans. SARS has sickened more than 3,200 people worldwide and killed at least 156.

After cracking the genetic code, as researchers in Canada and the United States did in recent days, the Hong Kong scientists agreed that it was a new version of the coronavirus, which can cause common colds, but unlike any seen before.

"If this virus had been very close to the rat virus, mouse virus or pig virus, one could clearly say this is the origin," said Malik Peiris, another microbiologist at the university.

"But what this is telling us is that in fact, this virus is not close to any of the known human or animal viruses," Peiris said. "It is something that is new to science."

Asked about the possibility that the virus was man-made, Peiris said there was no chance of that.

"That whole genome is essentially new," he said. "Nature has been the terrorist throwing up this virus."

Yuen said that the only people who appear to have antibodies against the SARS virus are patients who have recovered, but they want to test animals to see if their blood contains antibodies. Yuen declined to say which animals would be tested.

Canadian researchers over the weekend first published the entire genetic sequence of the SARS virus.

Officials at the US Centres for Disease Control and Prevention released their own sequencing of the gene code on Monday, and said a key question was whether it came from animals, as many have suspected.

Hong Kong has been particularly hard hit by SARS, with a little more than one-third of the world's total cases and deaths.

Yuen said the Hong Kong scientists suspect that the SARS virus may have mutated into a more virulent form at Amoy Gardens - a Hong Kong apartment complex where about 300 residents were sickened. Peiris said a new genetic sequencing is being conducted to try to say for sure.

Infected people from Amoy Gardens have not responded so well to a combination of the antiviral drug ribavirin and steroids, which has been helping many other Hong Kong SARS patients.

The cocktail treatment had been helping about 90 percent of the Hong Kong patients, but once hospitals started filling up with a big number of people from Amoy Gardens, the number of patients who responded well to the treatment fell to about 80 percent, Yuen said. He did not break down responses from Amoy Gardens patients, however.

About 60 percent of the Amoy Gardens patients suffered from diarrhoea - a symptom not seen in many patients from other areas, Yuen said. Many showed signs of improvement before deteriorating again.

"This led us to believe that the virus may have changed somehow at Amoy Gardens, but we are still investigating," Yuen said.

Yuen said they have found some antiviral drugs other than ribavirin that seemed effective for treating SARS, but he declined to name them, saying that further tests were needed.

Understanding the origin of SARS, which was believed to have spread from Guangdong in southern China via Hong Kong to dozens of countries including Singapore, Canada and Vietnam, would be important to prevent such transmission from happening again, Peiris said.

What did SARS ever do to us?

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