August 2, 2006

US researchers fail to find bird flu transmissible among human
 

Scientist who tried to combine a common flu virus with the H5N1 bird flu virus to create a pandemic virus have failed, giving hope that it may be difficult for bird flu to mutate into a form that is easily transmissible among humans, according to a report in Proceedings of the National Academy of Sciences.

Researchers from the US Centres for Disease Control and Prevention (CDC) in Atlanta infected ferrets with genetically engineered versions of H5N1 bird flu but found other ferrets caged nearby were not infected. Ferrets were used because they catch colds in ways similar to humans.

The hybrid flu versions also appeared less virulent than their parent strains.

Dr Jackie Katz of the CDC's Influenza Branch said one way viruses can evolve into epidemic and pandemic forms is by mixing their genetic material with other viruses. Researchers mixed a sample of H5N1 virus taken in 1997 with genes from an H3N2 flu virus.

However, the head of CDC Dr Julie Gerberding, said that the experiment did not mean that H5N1 would never be able to evolve into a form transmissible from person to person. It simply means it would be difficult for it to do so, Gerberding added, saying there are many combinations yet to be tried that may produce that deadly version.