The basis for the size differences in plaques produced by variants of encephalomyocarditis (EMC) virus

Abstract

A sulfated polysaccharide in agar has been shown to be responsible for the size differences in the plaques produced by two variants of encephalomyocarditis (EMC) virus. Sulfated polysaccharides (using sodium dextran-SO 4 as a model compound) interfere with the adsorption of the wild-type ( r +) virus, but not the large-plaque ( r) variant. At a constant virus concentration, the effect of dextran-SO 4 is concentration dependent, and is also a function of pH and ionic strength. Probably an ionic interaction between sulfated polysaccharide and r + virus effectively binds or restricts the virus and thereby reduces the absolute number of plaque-forming units adsorbed to susceptible cells per unit time and reduces the plaque size in contrast to the r variant, which is not bound by the sulfated polymer in the agar overlay.