Courtesy of WHO Collaborating Centre for Reference and Research on Influenza, National Institute of Infectious Diseases, Japan
A mutated strain of the H7N9 influenza virus that infects humans is resistant to the antiviral drug Tamiflu. Becoming drug resistant does not appear to affect the ability of the virus to infect cells.
In contrast, when the seasonal flu virus becomes drug resistant, its ability to move among hosts and grow within them is reduced. The mutated, drug resistant H7N9 virus, however, was still able to infect cultured human cells and spread between laboratory animals as efficiently as nonmutated strains, researchers report December 10 in Nature Communications.
H7N9 is still better adapted to infect birds and, so far, has not had sustained transmission among humans.