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New strain of influenza contains avian, swine flu genes
WASHINGTON ― A new strain of swine influenza ― H2N3, which belongs to the group of H2 influenza viruses that last infected humans during the 1957 pandemic, has been identified by researchers. However, this new strain has a molecular twist: It is composed of avian and swine influenza genes.These findings provide further evidence that swine have the potential to serve as a "mixing vessel" for influenza viruses carried by birds, pigs and humans. It also supports the need to continue monitoring swine ― and livestock workers ― for H2-subtype viruses and other influenza strains that might someday th reaten swine and human health.A research team studied an unknown pathogen that in 2006 infected two groups of pigs at separate production facilities. Both groups of pigs used water obtained from ponds frequented by migrating waterfowl. Molecular studies indicated the unknown pathogen was an H2N3 influenza virus that is closely related to an H2N3 strain found in mallard ducks. But this was the first time it had been observed in mammals. In the newly isolated swine H2N3, the avian H2 and N3 gene segments mixed with gene segments from common swine influenza viruses. This exchange, and additional mutations, gave the H2N3 viruses the ability to infect swine. Agricultural Research Service veterinarians Juergen Richt, Amy Vincent, Kelly Lager and Phillip Gauger conducted research with Iowa State University visiting scientist Wenjun Ma, I.S.U. veterinarian Bruce Janke and other colleagues at the University of Minnesota and St. Jude Childrens Research Hospital. 
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