Effects of Cyclosporin A on Cell Fusion in a Monkey Kidney Cell Line Persistently Infected with Measles Virus

The authors studied the effects of immunosuppressive peptide cyclosporin A (CsA) on cell fusion efficiency in cells persistently infected with measles virus (448-PI-Vero cells). Treatment of 448-PI-Vero cells with 5 microM CsA enhanced the infusion. In addition, the expression of measles virus antigen on cell surface was increased by treatment with CsA. The addition of phenothiazine, an anti-calmodulin drug, enhanced the fusion of 448-PI-Vero cells in the presence of CsA, although treatment with phenothiazine alone did not affect polykaryocyte formation. The enhancement of fusion efficiency in 448-PI-Vero cells by CsA was suppressed by oligopeptide Z-D-Phe-Phe-Gly, a synthetic oligopeptide that inhibits fusion induced by measles virus. Since the cell content of major virus-specific polypeptides, such as hemagglutinin, nucleoprotein or matrix protein is the same as in untreated controls, this fusion enhancement may be related to transport and accumulation of measles virus glycoproteins.