The titer of
complement-fixing (
CF) antigen of human cytomegalovirus (CMV) strain C87 was not reduced by 10 cycles of freezing and thawing or by storage at 4 C for two months, although the virus was labile at 37 C and 100 C. The rapid increase in titers of
CF antigen and plaque-forming units was seen from days 3 through 6 after
infection; however,
CF antigen was detected 24 hr after
infection. The molecular weight of
CF antigen was estimated by gel filtration to be greater than 1.5 X 10(7) daltons. Electrophoresis of CF
antigens from five strains of human CMV (AD169, C87, Espilant [Esp.], Davis, and Towne) in a gradient
polyacrylamide gel slab in the presence of
sodium dodecyl sulfate revealed two specific
polypeptides with molecular weights of 140,000 and 66,000 daltons, respectively. The smaller
polypeptide was glycosylated. Preparations of
CF antigen from murine CMV and herpes simplex virus type 1 contained
polypeptides of 140,000 and 145,000 daltons, respectively. However, the
polypeptide with a molecular weight of 66,000 daltons was seen only in preparations of human CMV.