Size of infectious DNA from human and murine cytomegaloviruses

Viral DNA was isolated from human and murine cytomegalovirus by equilibrium centrifugation in cesium chloride gradients. The size of the DNA was measured relative to T4 DNA by velocity sedimentation in neutral glycerol gradients, and fractions were assayed for infectious DNA. Infectious murine cytomegalovirus DNA sedimented as a single peak with an estimated molecular weight of 136 X 10(6). Infectious human cytomegalovirus DNA was detected in two peaks with molecular weights of 130 X 10(6) and 150 X 10(6).