FIG. 6.
Immunofluorescence analysis of NP expression in WT and STAT1−/− MEFs infected with WSN virus. Cells were infected with WSN virus (MOI = 2) and stained with a monoclonal antibody against NP 14 h p.i. (A and D) Different-magnification fields of STAT1−/− cells. The majority of the cells showed a cytoplasmic NP staining, indicative of a late phase of virus replication. (B and C) Low magnification of two different fields of WT-infected cells. Although cell densities were roughly similar between the WT and STAT1−/− samples, only a few WT cells showed positive NP staining. (E and F) Higher magnification of individual positive-stained WT cells. Note that the majority of the NP staining is nuclear, which indicates a delayed or abortive viral replication.