title: The amino terminus of the vaccinia virus E3 protein is necessary to inhibit the interferon response.
abstract: Vaccinia virus (VACV) encodes a multifunctional protein, E3L, that is necessary for interferon (IFN) resistance in cells in culture. Interferon resistance has been mapped to the well-characterized carboxy terminus of E3L, which contains a conserved double-stranded RNA binding domain. The amino terminus of E3L has a Z-form nucleic acid binding domain, which has been shown to be dispensable for replication and IFN resistance in HeLa and RK13 cells; however, a virus expressing E3L deleted of the amino terminus has reduced pathogenicity in an animal model. In this study, we demonstrate that the pathogenicity of a virus expressing E3L deleted of the amino terminus was fully rescued in type I IFN receptor knockout (IFN-α/βR(-/-)) mice. Furthermore, this virus was IFN sensitive in primary mouse embryo fibroblasts (MEFs). This virus induced the phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α) in MEFs in an IFN-dependent manner. The depletion of double-stranded RNA-dependent protein kinase (PKR) from these MEFs restored the IFN resistance of this virus. Furthermore, the virus expressing E3L deleted of the amino terminus was also IFN resistant in PKR(-/-) MEFs. Thus, our data demonstrate that the amino terminus of E3L is necessary to inhibit the type I IFN response both in mice and in MEFs and that in MEFs, the amino terminus of E3L functions to inhibit the PKR pathway.
authors.affiliation: School of Life Science, Arizona State University, Tempe, Arizona, USA.
authors.forename: Stacy D
authors.initials: SD
authors.lastname: White
authors.forename: Bertram L
authors.initials: BL
authors.lastname: Jacobs
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D005260:Female; D006367:HeLa Cells; D006801:Humans; D007370:Interferon Type I / Q000276:immunology*; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D018345:Mice, Knockout; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D011817:Rabbits; D053633:Receptor, Interferon alpha-beta / Q000235:genetics / Q000276:immunology; D014615:Vaccinia / Q000235:genetics / Q000276:immunology* / Q000821:virology; D014616:Vaccinia virus / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*
chemical_list: C081374:E3L protein, Vaccinia virus; D007370:Interferon Type I; D016601:RNA-Binding Proteins; D014764:Viral Proteins; D053633:Receptor, Interferon alpha-beta