Fig. 1.
Multicycle growth kinetics of wild-type rPVM and rPVM mutants lacking one or both NS proteins in IFN-competent and incompetent cell cultures. (A) Replicate cultures of BHK-21 cells or MEF from C57BL/6 or B6.IFNAR0/0 mice were infected with rPVM or the ΔNS1, ΔNS2 or ΔNS1ΔNS2 mutants at an MOI of 0.01 PFU per cell. At the indicated time points, cells and medium were harvested, clarified, and flash frozen. In addition, peritoneal macrophages from C57BL/6 or B6.IFNAR0/0 mice (B) or RAW 264.7 cells (C) were infected as described for panel A. At the indicated time points, the medium supernatants were taken and flash frozen, and fresh medium was added. Virus titers were determined by plaque assay. For all experiments, each time point for each virus is represented by duplicate cultures. Mean values of two independent experiments are shown, with standard error of the means indicated.