In vitro mouse cytomegalovirus infection of mouse tracheal epithelial cells requires the presence of other cell types.

Recently, methods have been developed to culture dissociated tracheal epithelial (TE) cells. Attempts were made to infect these epithelial cells with mouse cytomegalovirus (MCMV) to see if the dissociated epithelial cells share characteristics of infection with MCMV-infected tracheal organ cultures. When isolated TE cells were incubated with MCMV at multiplicities between 0.10 and 2.0, no infection or minimal infection resulted. Centrifugation of virus onto the TE cell sheets also resulted in only minimal infection. If MCMV-infected mouse embryo fibroblasts were added to cultures of TE cells, however, the TE cells subsequently became infected. TE cells could also be infected by incubating MCMV with mixed cultures of uninfected fibroblasts and TE cells. The epithelial nature of infected cells was confirmed by electron microscopy. Reconstruction experiments demonstrated that fibroblast-mediated infection of mouse TE cells with MCMV was not simply due to the large amounts of virus provided by the infected fibroblasts. It is suggested that cell-cell contact, or fusion with infected cells is required for productive infection of TE cells with MCMV.