DIFFERENCES IN CYSTINE DEPENDENCE AND CHROMATOGRAPHIC BEHAVIOR BETWEEN TWO TYPE 4 ECHOVIRUS STRAINS.

Wallis, Craig (Baylor University College of Medicine, Houston, Tex.), and Joseph L. Melnick. Differences in cystine dependence and chromatographic behavior between two type 4 echovirus strains. J. Bacteriol. 89:1310-1313. 1965.-Type 4 strains of echovirus, which are known to differ in the ease in which they can be neutralized, have been found to differ in other properties also. The prototype strain (Pesascek) differed from a readily neutralizable strain (DuToit) in that the Pesascek strain could be stabilized by cystine to thermal inactivation. Furthermore, the prototype virus required cyst(e)ine for growth under agar, whereas the DuToit strain was not affected. The viruses also reacted differently on anion-exchange resins. Pesascek virus had surface groups capable of exchanging for phosphate ions and, thus, was readily adsorbed, whereas DuToit virus was not bound by the resins under the same conditions. Only a small fraction of Pesascek virus was found to pass through the resin column. This fraction bred true, in that it yielded progeny that behaved like DuToit in not exchanging for phosphate. However, in neutralization tests, the progeny of this fraction retained the immunological property of the parent Pesascek virus.