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 5 days 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.