title: A mammalian 2-5A system functions as an antiviral pathway in transgenic plants.
abstract: Resistance to virus infections in higher vertebrates is mediated in part through catalysis of RNA decay by the, interferon-regulated 2-5A system. A functional 2-5A system requires two enzymes, a 2-5A synthetase that produces 5'-phosphorylated, 2',5'-linked oligoadenylates (2-5A) in response to double-stranded RNA, and the 2-5A-dependent RNase L. We have coexpressed these human enzymes in transgenic tobacco plants by using a single plasmid containing the cDNAs for both human RNase L and a low molecular weight form of human 2-5A synthetase under control of different, constitutive promoters. Expression of the human cDNAs in the transgenic plants was demonstrated from Northern blots, by specific enzyme assays, and by immunodetection (for RNase L). Infection of leaves, detached or in planta, of the coexpressing transgenic plants by tobacco mosaic virus, alfalfa [correction of alfafa] mosaic virus, or tobacco etch virus resulted in necrotic lesions. In contrast, leaves expressing 2-5A synthetase or RNase L alone and leaves containing the plasmid vector alone produced typical systemic infections. While alfalfa mosaic virus produced lesions only in the inoculated leaves regardless of the concentration of virus in the inoculum, high, but not low, levels of tobacco etch virus inoculum resulted in escape of virus to uninoculated leaves. Nevertheless, there was a substantial reduction of tobacco etch virus yield as measured by ELISA assay in the coexpressing transgenic plants. These results indicate that expression of a mammalian 2-5A system in plants provides resistance to virus infections.
authors.affiliation: Center for Biotechnology and Department of Plant Pathology, University of Nebraska, Lincoln 68583-0722, USA.
authors.forename: A
authors.initials: A
authors.lastname: Mitra
authors.forename: D W
authors.initials: DW
authors.lastname: Higgins
authors.forename: W G
authors.initials: WG
authors.lastname: Langenberg
authors.forename: H
authors.initials: H
authors.lastname: Nie
authors.forename: D N
authors.initials: DN
authors.lastname: Sengupta
authors.forename: R H
authors.initials: RH
authors.lastname: Silverman
mesh_terms: D000227:Adenine Nucleotides / Q000235:genetics / Q000378:metabolism*; D000998:Antiviral Agents / Q000235:genetics / Q000378:metabolism*; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006367:HeLa Cells; D006801:Humans; D009843:Oligoribonucleotides / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D010947:Plants, Toxic; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000276:immunology*
chemical_list: D000227:Adenine Nucleotides; D000998:Antiviral Agents; D009843:Oligoribonucleotides; C023505:2',5'-oligoadenylate; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease