Fig. 4.

Susceptibility of primary murine alveolar epithelial cells to infection by murine coronavirus, MHV-1. (A) Murine cells were cultured as either an ATI or ATII cell phenotype for 5 days, then were inoculated with MHV-1 for 12 h or 24 h. Infection was analyzed by immunofluorescence assay of viral nucleocapsid protein (green) and nuclei were stained with DAPI (blue). (B) Cells were cultured on fibronectin (ATI phenotype) and inoculated with MHV-1 or mock-inoculated. Cells were photographed on phase contrast at 24 h p.i. (C) Infection of MHV-1-inoculated ATI and ATII cells was analyzed by plaque assay of supernatant medium at the indicated times. The mean virus titers and standard errors from four replicate experiments are shown.