Murine cytomegalovirus infection in a non-permissive line of mouse fibroblasts.

A line of murine cytomegalovirus (MCMV)-resistant cells was derived from mouse embryo cultures. The virus penetrated the nuclei of these resistant cells efficiently and a small amount of viral gene transcription occurred, although no viral DNA synthesis was detected. Synthesis of cellular DNA, RNA and protein continued unabated, and the infected cells grew at the same rate as uninfected cells. The block in virus replication in these cells appears to be between early transcription and viral DNA synthesis.