FIG. 4.

Restoring either K1L or C7L to vK1L⁻C7L⁻ restores the IFN resistance phenotype. Huh7 (A) or MCF-7 (B) cells were pretreated with 0 or 200 U/ml of hIFN-β for 24 h and infected by the indicated viruses at an MOI of 5. The viral yields at 24 hpi were determined. vK1L⁻C7L⁻ is a VACV mutant specifically deleted of K1L and C7L genes, as previously reported (19). C7L-rev and K1L-rev were derived from vK1L⁻C7L⁻ by restoring C7L and K1L, respectively (18, 19).