SARS146; animal link

Scientists have discovered the first clue to the origins of the SARS virus, identifying a virtually identical microbe in two small mammals, and possibly a third, that are eaten as delicacies in China.

The findings, announced on Friday, prompted Chinese officials to ban sale of animals to stem the spread of the disease and prevent new outbreaks, WHO officials said. The findings could be a crucial development in the battle against SARS, which has stricken at least 8,117 people and killed at least 689 worldwide.

Discovering the source of the virus would be critical for determining how the infection arose. It could also allow authorities to eradicate reservoirs in nature where the virus could hide. That could allow the illness to be eradicated. 8216;8216;We believe the window is still open to eradicate this disease,8217;8217; said Klaus Stohr, WHO8217;s top SARS scientist.

Since SARS emerged in November, scientists have speculated that the disease may have originated when a previously unknown virus mutated in a way that allowed it to jump from an animal to humans. That is often how new human illnesses develop.

The long-sought discovery came when researchers from the University of Hong Kong and the Chinese government tested 25 animals from eight species sold at an animal market in Guangdong, where the disease first emerged. The tests found a virus that appeared virtually identical to the SARS virus in saliva and faeces of six catlike animals, known as masked palm civets.

The researchers isolated the virus from four of the animals and found pieces of genetic material from the microbe in two others. Tests also showed genetic evidence of the virus in the faeces of a raccoon dog.

Genetic analysis of the virus from the animals found it was identical to the SARS virus from human patients except that it lacked one sequence. The missing genetic material carries instructions for the production of a small protein, known as a peptide, and may have been the change that allowed the virus to jump to humans, Stohr said.

8216;8216;The lack of this peptide may have helped the virus transmit efficiently from human to human,8217;8217; Stohr said. 8216;8216;Perhaps that missing piece of protein is just the trick, the little difference between a harmless animal virus and a human pathogen. That8217;s a bit of speculation, but this is one hypothesis.8217;8217;

The civets appear to be most likely candidates, since the virus was found in more of these animals than any other. In addition, China apparently began importing civets in significant numbers from Vietnam in the past year, Stohr said.

8216;8216;That would fit with the occurrence of this disease,8217;8217; Stohr said.

8216;8216;What these findings mean is that the SARS coronavirus exists outside humans,8217;8217; Stohr said. 8216;8216;That means there8217;s a public health risk and that someone dealing with these animals or handling them could become infected.8217;8217;

If the animals are spreading the virus, it is more likely occurring when they are handled or slaughtered, and not when they are eaten, because cooking would kill the virus, Stohr said. LAT-WP