Neuraminidase mutations conferring resistance to laninamivir lead to faster drug binding and dissociation.

The neuraminidase (NA) inhibitors oseltamivir and zanamivir are administered twice daily for 5days for treatment of influenza. Laninamivir is a 7-methoxy derivative of zanamivir, but a single dose is effective when taken as the laninamivir octanoate prodrug. We show here in IC50 kinetics assays and a solid phase reactivation assay that compared to zanamivir laninamivir also demonstrates slow binding to but slower dissociation from multiple wild type NAs. A D197E mutation in an influenza B and an E119G in an N9 neuraminidase which confer 15- and 150-fold resistance to laninamivir result in faster binding and dissociation. Despite similar IC50s our assays demonstrate more rapid dissociation of laninamivir from clade 1 compared to 2 H5N1 NAs.