Alteration of the syncytium-forming property of XC cells by productive Moloney leukemia virus infection.

The effect of productive murine leukemia virus (MuLV) infection of the syncytium-forming property of XC cells was studied MuLV-Moloney-infected XC cells, designated XC(M), initially went through a period of spontaneous syncytium formation. The syncytia then disappeared, and XC(M) cells continued to propagate and produce both infectious MuLV and MuLV group-specific antigens. However, XC(M) cells became refractory to syncytium formation that was induced by Kirsten, Friend, Rauscher, and Moloney strains of murine oncornaviruses. These data suggest that XC(M) cells lost their syncytium-forming ability as a result of productive MuLV infection.