Human SARS virus not identical to civet virus

GENEVA—Rare Chinese masked palm civet cats, a medicinal food animal in Southern China eaten to reduce the chance of winter infections like colds and flu, contain the coronavirus thought to cause severe acute respiratory syndrome (SARS), Chinese and Hong Kong scientists have announced. So did a single racoon dog tested. Coypu and rabbits were free of the virus, but common Chinese pets and food animals like dogs, cats, sheep and goats remain untested, Klaus Stöhr, director of the World Health Organization's global SARS laboratory network, told The Scientist Monday (May 26).The virus found in the civet cats is not identical to the coronavirus found in SARS patients; the human virus has 29 fewer nucleotides in the N-protein. "The human virus has a deletion. We think the N-protein is attached to the interior of the virus envelope, but our knowledge about this is schematic. We don't know what the protein is doing," Stöhr said.According to Stöhr, the deletion crosses two open reading frames, creating a new open reading frame that could encode 122 amino acids. "What that deletion means in terms of pathogenicity, species specificity, immunology, transmissibility is completely open," said Stöhr.The sequence of the animal virus was compared to 60 sequences of human SARS virus in a library available to the Chinese researchers. "With the exception of these 29 nucleotides they were identical," said Stöhr. "But there was one human virus which didn't have this deletion. This was one called 'GZ1'. But we don't know more about that sample, where it came from, what the person had when he became ill—we have no clue what it means at present."It is unfortunate that the many human coronavirus sequences now completed are not available to all researchers, said Stöhr. "Some are able to compare their sequences with 60 sequences, others with 30, and some of these are overlapping," he said. But there is no unified global SARS sequence database. "WHO [World Health Organization] must establish a genetic diversity databank. We would like everyone who is sequencing a virus to put up their sequences, so they could all be compared with each other," said Stöhr.Nevertheless a "reassuring piece of information" was released on the WHO network yesterday, Stöhr said. Ten food handlers from Guandong province—where SARS began in November 2002—have been tested for antibodies to the human SARS virus, and five had seroconverted (they had antibodies to the virus). "This could mean they'd had SARS and not reported it, or that they got it from their work." Reassurance came from the fact that the food-handlers' antibodies could inhibit both the human and the civet cat virus, said Stöhr.As for the disease control implications of the discoveries so far, according to Stöhr the existence of an animal reservoir "would certainly imply additional measures would need to be taken to stop re-infection of humans. We don't know if this is a potent reservoir, shedding enough virus to infect people, but from the seroconversion of food-handlers one would think it might be doing so."Meanwhile, according to China Daily, the Shenzhen administration is drafting legislation to forbid the hunting, processing, purchasing, slaughtering and consumption of wildlife, a drastic measure that could finish 5000 years of traditional cuisine in the region.Further data reported on the WHO network yesterday shows that all the six index cases in four cities in Guandong had either eaten wildlife, or had dealt with wildlife, particularly snakes, ten days before they fell ill, said Stöhr. "We don't know what the snakes mean, but broadly this appears to be another piece fitting into the pattern." "Now we have to take this animal virus and put it into susceptible primates," he said. That will indicate whether the virus could also infect humans. "Even then we will not learn if the animal virus is more or less pathogenic. Nor will we learn about the transmissibility of the virus." "We are extending the WHO SARS laboratory network to include an animal section," said Stöhr. "We've prepared a funding proposal to conduct trials in more common food or domestic animals, to see if they are susceptible to the virus and excrete it or fall ill. We've looked at chickens and pigs but we haven't looked at goats, sheep, dogs, or cats. "The epidemiological evidence would not suggest that these animals play a role, but we want to play safe."

Human SARS virus not identical to civet virus

Chinese data suggest human SARS virus sequence similar to civets' but contains deletion

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