Comparison of Buoyant Density of Two Mutants of ECHO 6 by Density Gradient Ultracentrifugation. ∗

Abstract

Summary

Mutants of ECHO 6 virus, designated m ⁺ and m, were ultracentrifuged separately and as mixtures in a cesium chloride density gradient. The density at the peak of infectivity for each mutant was corn-pared. A small density difference in the range of 0.001-0.004 g/cm³ was measured, with m the heavier mutant.