FIG 3.

Host restriction of cap-dependent and IRES-mediated translation. (A) Experimental plan. Features of VACV transcription, including the inhibition by AraC of intermediate and late gene expression, are indicated on the left. The plan to assess expression in VACV-infected cells from a transfected plasmid with a bicistronic gene encoding FLuc regulated by an intermediate promoter, followed by RLuc regulated by the CrPV IRES, is illustrated on the right. (B) HeLa and SAMD9^−/− cells were infected with 3 PFU/cell of ΔC7K1 and transfected 1 h later. Expression of FLuc was determined at 2, 4, 6, and 8 h after infection. (C) HeLa cells were infected in triplicate, as described for panel B, with ΔC7K1 or WT virus in the absence or presence of 40 µg/ml AraC and transfected with the bicistronic reporter plasmid. At 6 h after infection, the cells were lysed and FLuc and RLuc activities determined. Error bars represent SEM.