Human cytomegalovirions and dense bodies: glycopeptide analysis and mechanism of cell rounding and polykaryocytosis.

Human cytomegalovirions and dense bodies labeled with [14C]glucosamine were analyzed by means of sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis and autoradiography. The same glycopeptide composition was found in both cytomegalovirions and dense bodies. These consisted of at least 11 glycopeptides which ranged in molecular weight from 46,500 to over 170,000 daltons. Addition of purified human cytomegalovirus (CMV) at high multiplicity to confluent monolayers of human fibroblasts produced cell rounding and polykaryocytes containing 3 to 150 nuclei. The cell rounding was induced by the cytomegalovirions, but not by the cytomegalo dense bodies. Inhibition of protein synthesis, but not of DNA synthesis, prevented this effect, suggesting that cell rounding is protein mediated. In contrast, the formation of polykaryocytes by CMV was not affected by inhibitors of protein synthesis. UV irradiation of the virus, which abolishes infectivity, does not affect its fusion properties. CMV dense bodies, which contain very little or no DNA, also produce cell fusion although this effect is less pronounced than with virions. CMV-induced polykaryocytosis therefore appears to be a direct result of the interaction of cells with the input viral particles, a phenomenon usually referred to as early polykaryocytosis.