- WASHINGTON (Reuters) - The
SARS virus looks like a combination of viruses from birds and mammals,
Canadian researchers said on Monday.
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- The finding suggests that Severe Acute Respiratory Syndrome
arose just as many new strains of influenza do -- when a bird virus recombines
with a virus in a mammal to take on a form that can infect humans.
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- SARS swept across China and was exported as far as Canada
between November 2002 and May 2003, killing 774 people and infecting as
many as 8,000.
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- Experts eventually identified a new kind of coronavirus
as the cause of the disease, essentially an unusually severe form of pneumonia.
Such viruses cause a range of veterinary diseases but usually nothing worse
than the common cold in people.
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- David Guttman, a professor of evolutionary genomics at
the University of Toronto, compared the SARS virus genome to related coronaviruses.
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- About half the DNA looked like coronavirus sequences
taken from mammals, while half looked like coronaviruses normally found
in birds, Guttman reported in the January issue of the Journal of Virology.
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- A key gene called the spike gene looked to be a mix.
This gene seems to be important in allowing the virus to infect cells,
experts have said.
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- The merging of mammalian and avian viruses probably allowed
the spike gene to sneak past immune system sentinels.
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- "These recombination events have the potential to
create an entirely new structure essentially instantaneously," Guttman
said in a statement.
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- "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."
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- SARS coronavirus was found in raccoon-like animals called
civets in wildlife markets.
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- "It's possible that a civet picked up the virus
from a bird," Guttman said.
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- "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."
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- SARS has not been seen since it was brought under control
in June but health officials are watching warily for it to re-emerge.
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- "This will allow us to design more effective treatments
and respond more effectively to future outbreaks," Guttman said.
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- Comment
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- From Patricia Doyle, PhD
- dr_p_doyle@hotmail.com
- 12-17-3
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- It sounds like March 2003 all over again. Scientist
unknowingly infected with SARS travels outside of his country thus making
a pandemic SARS outbreaki possible.
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- I still believe that some virulent US cases diagnosed
as flu are really recombined SARS/Influenza.
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- New York State has added a death attributed to the Flui.
A 17 year old Albany, N. Y. student has died of Influenza.
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- Patricia
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