Biochemical analysis of Anagrapha falcifera NPV attachment to Spodoptera frugiperda 21 cells

The binding characteristics of Anagrapha falcifera nuclear polyhedrosis virus (AfNPV) to Spodoptera frugiperda 21 (Sf21) cells were investigated. The cells displayed an affinity of 4.7x10¹⁰ M^-1 with about 3,300 binding sites per cell. The biochemical nature of the AfNPV-binding sites on the cell surface was also partially identified. Our findings suggest that the binding- site moiety has a glycoprotein component, but that the direct involvement of oligosacccharides containing N-acetylglucosamine or sialic acid residues in binding is unlikely, and that AfNPV entry into Sf21 cells may be via receptor-mediated endocytosis.