Cells infected with human cytomegalovirus release a factor(s) that stimulates cell DNA synthesis

Culture supernatants of permissive and non-permissive cells infected with human cytomegalovirus (HCMV) contain a growth factor that enhances the DNA synthesis and mitotic activity of target cells. This cytomegalovirus growth factor CMV-GF) is a heat-stable, acid-labile polypeptide that is sensitive to trypsin and dithiothreitol. CMV-GF is an early product of the infected cells and defective virions are primarily responsible for its induction. Microtubule depolymerization is necessary for the induction of DNA synthesis by the CMV-GF, since taxol, an inhibitor of microtubule depolymerization, blocks its effect.