Avian influenza is mutating, but antivirals still work Researchers at Texas Biomed identified nine mutations in a bird flu strain from a person in Texas. The finding highlights a key concern about the H5N1 strains of avian influenza currently circulating in the U.S.: the speed at which the virus can mutate when introduced to a new host. In mouse studies, they found that compared to the bovine strain, the human strain replicated more efficiently, caused more severe disease and was found in much higher quantities in brain tissue. They also tested several FDA-approved antiviral medications to see if they were effective against both virus strains in cells. Next steps and recommendationsTexas Biomed is now exploring the human H5N1 mutations individually to determine which are responsible for increased pathogenicity and virulence.