Purification and characterization of the Hemagglutinin-Neuraminidase of Porcine rubulavirus LPMV

The Hemagglutinin-Neuraminidase (HN) from the LPMV strain of Porcine rubula virus was purified from virions by ultracentrifugation in a continuous 20-6 0% sucrose gradient and by ion exchange chromatography. The HN is a glycopr otein of 66 kDa constituted by 50.5, 13.3 and 13.6% of non polar, uncharged polar, and charged polar amino acids, respectively. The HN contains 4% of carbohydrates, its glycannic portion is constituted by Man, Gal, GlcNAc, Ga lBAc, and Neu5Ac in 3:3:4:1:1 molar ratios. The HN possesses hemagglutinati ng activity in the presence of erythrocytes from several animal species, in cluding human ABO, and treating the erythrocytes with neuraminidase or pron ase abolishes this activity. The binding specificity of the purified HN was determined by hapten inhibition assays, indicating that the hemagglutinati ng activity of the HN is specific for sialic acid and Neu5Ac alpha 2,3Gal-c ontaining structures.