FIG 2.

Identification of C9 as an IFN antagonist. (A) The diagram at the top shows the left portion of the WR genome, with the 17 ORFs deleted from the 6/2 mutant shaded gray. Black arrows indicate the direction of transcription. Lower diagrams depict four WR mutants, vΔ(13–18), vΔ(C9-C7), vΔ(C6-C3), and vΔ(C2-N2), with deletions of multiple ORFs. The green arrows and vertical lines indicate the replacement of WR ORFs by GFP regulated by the P11 promoter, in red. (B) IFN sensitivity of the viruses with deletions of multiple ORFs. A549 cells were untreated (lanes −) or treated with 2,000 IU/ml of IFN-β for 24 h (lanes +) and infected with 0.01 PFU/cell of the indicated virus. After 48 h, the lysates were analyzed by Western blotting using antibody to VACV, the L1 protein, and actin as a loading control. The positions of protein markers (in kilodaltons) are shown on the right. (C) The diagram at the top shows a portion of the WR genome containing ORFs 18, C9L, C8L, C7L, and C6L, with black arrows indicating the direction of transcription. The shaded ORFs were individually deleted to construct three deletion mutants, vΔC9, vΔC8, and vΔC7. The green arrows depict the replacement of an individual WR ORF by GFP regulated by the P11 promoter, in red. (D) The IFN sensitivity of the deletion mutants was determined as described in the legend to panel B.