FIG. 7.
Viral growth of Alfort-Jiv and Alfort-p447 in porcine PK-15 cells and effects on expression of IRF3 and the Mx protein. (A) Growth curves of cp CSFV Alfort-Jiv and non-cp CSFV Alfort-p447. Growth kinetics were determined on PK-15 cells infected at an MOI of 0.5. Titers of released virus were determined over a 2-day period at the indicated time points. (B) Virus titers obtained 24 h and 48 h after infection of untreated PK-15 cells (white bars) and PK-15 cell cultures treated with 1.1 nanogram of recombinant human IFN-α2a per milliliter at the time of infection (gray bars). Infections with cp Alfort-Jiv and non-cp Alfort-p447 were performed at an MOI of 0.5. (C and D) Expression of IRF3 (C) and Mx (D). Porcine PK-15 cells were infected with cp Alfort-Jiv and non-cp Alfort-p447 at an MOI of 1 and incubated for 24 h or 48 h at 37°C; noninfected (n.i.) cells served as a negative control. Cells were lysed at the time points indicated and subjected to immunoblot analysis. The samples (each containing the material from about 2 × 104 cells) were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions, transferred onto nitrocellulose, and incubated with an antiserum against porcine IRF3 (C). For the detection of Mx, the samples each contained material from about 2 × 105 cells, and anti-human Mx MAb M143 was used (D). Ten nanograms of recombinant human IFN-α2a per milliliter was used as a positive control for the expression of the Mx protein. Due to the expression of very large amounts of the Mx protein after treatment of cells with IFN, an about 10-times-shorter exposure time of the autoradiograph is shown for this lane.