Immunochemical characterization of Lymantri dispar NPV hemagglutinin: protein-carbohydrate interaction.
The agglutination of chicken erythrocytes by Lymantria dispar nuclear polyhedrosis virus polyhedrin has been shown to provide specific virus identification. Selected mono- and oligosaccharides, present in blood group substances, were assayed by the Land-steiner hapten inhibition technique for specific inhibition of polyhedrin hemagglutination. N-acetylgalactosamine and N-acetylglucosamine inhibit to the greatest extent; galactosamine, glucosamine and fucose to a lesser extent. The hapten inhibition data suggest that a monosaccharide possessing an equatorial 2-acetamido group interacts most avidly with the polyhedrin-combining site. Bergold demonstrated that the polyhedrin dissociates into six subunits at a pH greater than 10.0. Diafiltration equilibrium and Scatchard analysis indicate that N-acetylgalactosamine binds most avidly to the polyhedrin (Kd = 1.7 X 10(-6)) which contains six available sites, suggesting that one hemagglutination site resides on each subunit. Since virions derived in vivo and polyhedrin are serologically cross-reactive, this protein-carbohydrate interaction may play a role in host infectivity by providing a receptor site for virus attachment to target cells.