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Study Yields Hybrid Flu Strains That Cause Severe Disease (2010)

NIAID-supported researchers at the University of Wisconsin, Madison, have found that when H5N1 avian influenza reassorts (combines) with a seasonal flu strain, the results can be a highly pathogenic (causing severe disease) avian influenza. Led by Yoshihiro Kawaoka, D.V.M., Ph.D., the team used reverse genetics to generate 254 combinations of reassortant viruses between a low-pathogenic avian H5N1 virus and a human seasonal H3N2 virus. The study found that 22 viruses were more pathogenic for mice than the original H5N1 virus and three viruses caused extremely severe disease. The findings underscore the critical need for virus genetic surveillance and the importance of monitoring influenza strains in wild birds, animals, and people.


C Li et al. Reassortment between avian H5N1 and human H3N2 influenza viruses creates hybrid viruses with substantial virulence.  Proc Natl Acad Sci DOI: 10.1073/pnas.0912807107 (2010).

Last Updated March 12, 2013

Last Reviewed March 12, 2013