WASHINGTON (Reuters) - The SARS virus looks like a combination of viruses from birds and mammals, Canadian researchers said on Monday.
David Guttman, a professor of evolutionary genomics at the University of Toronto, compared the SARS virus genome to related coronaviruses.
About half the DNA looked like coronavirus sequences taken from mammals, while half looked like coronaviruses normally found in birds, Guttman reports in the January issue of the Journal of Virology.
A key gene called the spike gene that is thought to be important in allowing the virus to infect cells looked to be a mix.
The merging of mammalian and avian viruses probably allowed the spike gene to evade immune system sentinels.
“These recombination events have the potential to create an entirely new structure essentially instantaneously,” Guttman said in a statement. “Since our immune systems have never seen this new viral form, it is more difficult for them to respond to it in a timely and effective manner.”
SARS coronavirus was found in raccoon-like animals called civets in wildlife markets. “It’s possible that a civet picked up the virus from a bird,” Guttman said.
“This could have created the opportunity for a very rare recombination event that produced a virus with a new host range. Basically, the recombinant virus is infectious to humans, while the two parent viruses are not. This new virus likely then spread to humans due to poor hygiene and close quarters in the food markets of southern China.”
SARS has not been seen since it was brought under control in June but health officials are watching warily for it to re-emerge.
“This will allow us to design more effective treatments and respond more effectively to future outbreaks,” Guttman said.
Source: J Virology 2004;78:76-82. [ Google search on this article ]
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