Assays for Functional Binding of Plasminogen to Viral Proteins

Cleavage of the hemagglutinin (HA) molecule by proteases is a prerequisite for the infectivity of influenza A viruses. Plasminogen binds to the viral glycoprotein neuraminidase (NA), and NA-bound plasminogen is activated to plasmin, which cleaves the HA of influenza A/WSN/33 (WSN) (H1N1) virus. Here we present assays for detecting functional plasminogen binding to the influenza virus NA.