FIG 1.

Expression of functionally active IFN-λ (IL-28) protein from VSV. (A) Genomic diagrams of the VSV vectors generated in this study. All five genes encoding the nucleocapsid (N), the phosphoprotein (P), the matrix protein (M), the glycoprotein (G), and the RNA-dependent RNA polymerase (L) were present in the viruses. The mouse IFN-λ2 (IL-28A) gene was inserted either upstream of the L gene in the 5th position (VSV28.5) or upstream of the N gene in the 1st position (VSV28.1). Control viruses with either no insert (VSV) or the GFP gene inserted in the 1st position (VSVGFP.1) are also depicted. (B) Immunoblot analysis of glycosolated or unglycosolated IFN-λ protein expressed in the lysates or media collected from BHK cells infected with the designated viruses at either 6 or 12 h p.i. Molecular mass values are indicated. (C) Immunoblot of STAT1 (p-STAT1α [91 kDa] and a splice variant, STAT1β [84 kDa]) phosphorylation in MMHD3 cells incubated for 30 min with media from either MMHD3 or BHK cells collected after a 24-h infection with VSV, VSV28.5, or VSV28.1. Media were treated with or without soluble B18R protein to block IFN-α/β before transfer onto MMHD3 cells as designated. Molecular mass values are indicated.