Laboratory experiments in mice showed that the avian flu (H5N1) was converted into a pandemic form by a gene segment from H3N2, a seasonal human flu virus. This is first virus generated in a laboratory study that was more virulent than its parent strains. "H5N1 virus has never acquired the ability to transmit among humans, which is why we haven't had a pandemic. The worry is that the pandemic H1N1 virus may provide that nature in the background of this highly pathogenic H5N1 virus," says Kawaoka.
Source: http://www.examiner.com/x-30836-Madison-Science-News-Examiner~y2010m2d25-Virus-hybridization-could-cause-pandemic-bird-flu 
















