Fig. 1.

Characterization of a human cell line stably expressing B/NS1. Western blot analysis (a) and immunofluorescence analysis (b) of HEp2 cells stably expressing V5-tagged A/NS1 or B/NS1. (c) B/NS1 blocks IFN induction in response to virus infection. Cells were infected with PIV5(CPI-) at an m.o.i. of 5 p.f.u. cell⁻¹, before supernatants were harvested at the indicated times, UV inactivated and titrated by biological EMCV CPE-reduction assay. Mean values of triplicate experiments are shown. Error bars represent standard deviation (SD). (d) Western blot analysis of lysates from HEp2 cells treated, or not, for 20 h with 1000 IU ml⁻¹ rIFNα. The indicated proteins were detected with specific antibodies. (e) Specific co-immunoprecipitation of ISG15 and PKR with V5-B/NS1 from lysates of IFN-stimulated (or mock-treated) cells. Asterisks indicate antibody heavy and light chain. ISG15 and potential ISG15-conjugates are indicated by (^). Molecular weight markers (kDa) are indicated to the right.