Influenza virus nucleoprotein (NP) is a structural protein which encapsidates the negative strand viral RNA. NP is one of the main determinants of species specificity.
Monoclonal HB65 is a classic reagent for the detection of flu virus particles. It can be used for IP, WB and IHC. In particular it is the only monoclonal that works for IHC on formalin fixed tissue sections ( see reference ).