Figure 4.

Interferon sensitivity of the rPR8 viruses in mouse epithelial cell lines. A. Growth curve of the rPR8 mutant viruses in M1 cells. Monolayers of M1 cells were infected with each of the rPR8 viruses at MOI = 1. Cell supernatants were collected at 0, 8, 24 and 48 hpi. Viral titer was assessed by plaque assay. B. Growth curve of the rPR8 mutant viruses in M1 cells in the presence of IFN-β. Monolayers of M1 cells were treated with 200U/ml of murine IFN-β. Twenty-four hours post treatment; monolayers were infected with each of the rPR8 viruses at MOI 1. Cell supernatants were collected at 0, 8, 24 and 48 hpi. Viral titer was assessed by plaque assay. Values are shown as average +/- standard deviation.