Scientists report that H5N1 avian influenza viruses may be adapting to pigs, as evidenced by the finding that H5N1 viruses isolated from pigs in Indonesia were less harmful to mice than were H5N1 viruses from chickens.

The finding suggests that in growing in pigs, the virus may have become less harmful to mammals in general, the authors report. That sounds reassuring, but the authors say it may mean the virus is one step closer to turning into a human pandemic strain.

In the study, scientists from Japan and Indonesia collected viruses from chickens and pigs in Indonesia, grew them in laboratory cell cultures, and used them to infect mice. They found that the viruses from pigs were less lethal to mice than the viruses from chickens, according to their recent report in the Archives of Virology.

“We found that swine isolates were less virulent to mice than avian isolates, suggesting that the viruses became attenuated during their replication in pigs,” the report states.

http://www.cidrap.umn.edu/cidrap/content/influenza/avianflu/news/mar3109swine-jw.html

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