Abstract
Human osteogenic sarcoma cells transformed by murine sarcoma virus (R970) showed restricted growth of human cytomegalovirus (HCMV). Virus was attached to the same extent as in human fibroblasts. HCMV growth was blocked at early stages after virus penetration. Splitting of infected R970 cultures resulted in infection of all cells. In experiments using synchronized R970 cells it was found that factor(s) associated with the S-phase of the cell cycle might be necessary for establishment of the infection.