Comparison of the Polypeptides of Several Strains of Human Cytomegalovirus

This 1977 study characterized the polypeptide composition of human cytomegalovirus (CMV) using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Researchers purified CMV virions from infected human embryo lung fibroblast cells by differential centrifugation and sucrose gradient separation, achieving approximately 100-fold enrichment while minimizing host cell protein contamination. Analysis of the Towne strain revealed at least 32 distinct polypeptides with molecular weights ranging from 13,500 to 235,000 daltons. Eight polypeptides were identified as glycoproteins. The researchers then compared polypeptide patterns across four independent CMV strains: Birch, AD169, C87, and Towne. Despite originating from different sources and having different passage histories, all four strains displayed remarkably similar polypeptide compositions in both relative amounts and electrophoretic mobilities, with only minor variations. The authors concluded that the striking similarity in polypeptide composition among these four strains suggests they are closely related and may be antigenically related, contrasting with the greater strain variability observed in herpes simplex virus.

Key findings

• CMV virions contain at least 32 polypeptides with molecular weights between 13,500 and 235,000 daltons
• Eight polypeptides were identified as glycoproteins based on glucosamine labeling
• Four geographically and temporally distinct CMV strains (Birch, AD169, C87, Towne) showed remarkable similarity in polypeptide composition
• The polypeptide similarity among CMV strains suggests genetic and antigenic relatedness, consistent with DNA homology studies
• Purification method achieved approximately 100-fold enrichment of viral proteins over host cell proteins using sucrose gradient centrifugation