Analysis of the Bond between Encephalomyocarditis Virus and Its Human Erythrocyte Receptor by Affinity Chromatography on Virus-sepharose Columns

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Abstract
Affinity chromatography was used to analyse the bond between encephalomyocarditis (EMC) virus and glycophorin, the receptor for EMC virus on human erythrocytes. Between 60 and 80% of glycophorin added to virus-Sepharose columns was retained compared with 10 to 20% retention on glycine-Sepharose columns. Elution with 0.2 M-NaCl released about 80 to 90% of the retained glycophorin from virus-Sepharose columns but little from glycine-Sepharose. Glycophorin remaining on either the virus or glycine columns after 0.2 M-NaCl treatment was released with Triton X-100, suggesting that this material was aggregated and trapped non-specifically. The sensitivity of the EMC virus-glycophorin bond to 0.2 M-NaCl was confirmed by showing that the radiolabelled EMC virus that bound to human erythrocyte membranes in 0.02 M-phosphate buffer was released when washed with this buffer containing 0.2 M-NaCl. It was concluded that weak ionic interactions were involved in this virus-receptor bond. Treatment of glycophorin with neuraminidase prevented it binding to EMC virus-Sepharose indicating the requirement for sialic acid for receptor activity. However, other sialylated molecules did not bind. Only one chymotryptic peptide of glycophorin (CH0) bound to EMC virus-Sepharose, confirming that this peptide contains the virus-binding site as had been previously suggested using other techniques. The effects of two non-ionic detergents and two anionic detergents on the virus-glycophorin bond were examined. In each case a very low concentration of detergent disrupted the bond and the concentration required was in parallel with that which dissolved erythrocyte membranes. It appears that multivalent glycophorin aggregates are required for stable bond formation.