Immediate-early proteins of human cytomegalovirus strains AD 169, Davis, and Towne differ in electrophoretic mobility

Electrophoretic comparisons of the immediate-early (IE) proteins of three strains of cytomegalovirus (CMV) isolated from adenoidal tissue (Ad169), liver (Davis), and urine (Towne) of humans, have shown that they are distinguishable. Experiments based on “pulse-chase” radiolabeling, biosynthetic phosphorylation, and in vitro protein synthesis indicate that these differences are not the consequence of slow post-translational modification. Results of a comparison of high- and low-passage stocks of Towne virus suggest that these mobility differences reflect natural variation, rather than alterations resulting from propagation in tissue culture.