HEMAGGLUTINATION BY EQUINE INFECTIOUS-ANEMIA VIRUS

Equine infectious anemia (EIA) virus propagated on an equine dermal cell line agglutinated guinea pig erythrocytes. Viral fluids containing .apprx. 107.5 mean tissue culture infective doses/ml showed hemagglutinating (HA) titers from 16-32 units/0.05 ml. Results of CsCl equilibrium density gradient centrifugation revealed that the hemagglutinin was inseparable from the virus particles. The hemagglutination reaction persisted over a wide range of temperature and pH, and the absence of divalent cations did not decrease its activity. The HA activity was stable at 4.degree. C but not at 56.degree. C. The activity was destroyed by virus-disrupting lipid solvents and moderately sensitive to a proteolytic enzyme. Neuraminidase enhanced HA activity slightly. Phospholipase C had no effect on HA titer, although it completely inactivated infectivity. It was relatively stable to UV irradiation. The hemagglutinin appears to be closely associated with virus particles, and its activity is dependent on the presence of its lipids and proteins. Hemagglutination was inhibited by sera from horses infected with EIA virus. Hemagglutinin receptors on the erythrocytes were inactivated by a proteolytic enzyme and formaldehyde but were not influenced by neuraminidase, sodium deoxycholate or KIO4.