The structure of the influenza virus neuraminidases, the spatial organization of their active site, the mechanism of carbohydrate chains desialylation by. The interaction of influenza A viruses with the cell surface is controlled by the surface glycoproteins hemagglutinin ( HA) and neuraminidase. Sylte MJ( 1), Suarez DL. Influenza A viruses are classified into subtypes according to their two viral glycoproteins, hemagglutinin ( HA) and neuraminidase ( p 18,. Influenza virus neuraminidase ( NA) cleaves terminal sialic acid residues on oligosaccharide chains that are receptors for virus binding, thus. Influenza neuraminidase as a vaccine antigen.