Assays for Determining the Sialidase Activity of Influenza Viruses and Monitoring Influenza Virus Susceptibility to Neuraminidase Inhibitors

Abstract

Three types of assays––colorimetric, fluorescent, and chemiluminescent––are used to determine the sialidase (neuraminidase: NA) activity of influenza viruses. The fluorescent assay is cost-effective and applicable for many laboratories and is, therefore, commonly used for global monitoring of the NA inhibitor susceptibility of influenza viruses. Here, I describe, in detail, protocols for the fluorescence-based NA activity assay and the NA inhibition assay, which are used to determine the NA activity and NA inhibitor susceptibility, respectively, of influenza viruses.