The I222V Neuraminidase Mutation Has a Compensatory Role in Replication of an Oseltamivir-Resistant Influenza Virus A/H3N2 E119V Mutant

Oseltamivir-resistant A/H3N2 influenza isolates with or without the E119V and I222V neuraminidase (NA) mutations were recovered from an immunocompromised patient. Based on plaque size, yield assays, and NA activity, the impaired viral fitness of the E119V mutant was partially restored by the I222V NA mutation.