Presence of Haemagglutinin in the Envelope of Extracellular Vaccinia Virus Particles

Abstract

The relationship of vaccinia hemagglutinin (HA) to extracellular enveloped virus (EEV) was examined. EEV banded in csd gradients at a density of 1.cntdot.23-1.cntdot.24 g/ml coincident with a peak of HA activity. EEV of an HA+ vaccinia strain showed greater than 90% adsorption to rooster red blood cells (RBCs) as detected by infectivity and 3H-thymidine labeling, whereas intracellular naked virus (INV) of the HA+ strain and EEV of an HA- strain failed to show significant adsorption. The adsorption was specifically inhibited by antiserum to vaccinia. Adsorption kinetic experiments demonstrated a lack of temperature dependence on the total amount of EEV adsorbed. No elution of EEV from RBCs could be detected. The capacity of EEV to adsorb to RBCs was stable at 56.degree. C for 30 min.