MADISON, Wisconsin, February 26, 2010 (ENS) - Genetic interactions between avian influenza and human seasonal influenza viruses have the potential to create hybrid strains that combine the virulence of bird flu with the ability to spread like a pandemic, new research has found.
"With the new pandemic H1N1 virus, people sort of forgot about H5N1 avian influenza. But the reality is that H5N1 avian virus is still out there," says Yoshihiro Kawaoka, a virologist at the University of Wisconsin-Madison and senior author of the new study.
A new hybrid viral strain could be more capable of producing disease, or pathogenic, than either the bird flu virus or the human flu virus alone.
"Our data suggests that it is possible there may be reassortment between H5 and pandemic H1N1 that can create a more pathogenic H5N1 virus," Kawaoka said.
Professor Yoshihiro Kawaoka (Photo courtesy U. Wisconsin, Madison)
Two viruses infecting a single host cell can swap genetic material, or reassort, creating hybrid strains with characteristics of each parent virus.
Before the current study, hybrid viruses generated in lab studies had always been less virulent than parent strains. However, the new findings raise concerns that H5N1 and pandemic H1N1 viruses could reassort in individuals exposed to both viruses and generate an influenza strain that is both highly virulent and contagious.
The work was funded by the U.S. National Institutes of Health, the Japan Society for the Promotion of Science, the Ministry of Education, Culture, Sports, Science and Technology of Japan, and the Japan Science and Technology Agency.
In laboratory experiments in mice, a single gene segment from a human seasonal flu virus, H3N2, was able to convert the avian H5N1 virus into a highly pathogenic form.
The findings are reported in the current online early edition of the journal "Proceedings of the National Academy of Sciences."
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