Receptors for encephalomyocarditis virus on murine and human cells

The attachment kinetics of radiolabeled encephalomyocarditis virus were studied using established murine and human cell lines and murine and human erythrocytes. Unlabeled virus completely blocked the binding of labeled virus and virus subjected to pH 6.0 treatment bound at only one-tenth the rate of native virus. The initial rate constant at 0° calculated for human erythrocytes was 3.2 × 10^?10 cm³ min^?1 cell^?1. The rate constants for Friend leukemia cells and HeLa cells were, respectively, 200 and 2000 times faster. In contrast, no binding was observed to murine erythrocytes. The attachment of the virus to HeLa cells was found to be temperature independent over the range 0 to 40°. The attachment to murine cells (L-929 and Friend leukemia), however, was progressively reduced with increasing temperatures (0 to 40°) to about 0.01 of the rate at 0°. The decrease in binding at temperatures greater than 0° appears to be due to an increased rate of dissociation of the virus. It is proposed that both receptor number and viral affinity can influence pathogenicity.