Inactivated E. coli transformed with plasmids that produce dsRNA against infectious salmon anemia virus hemagglutinin show antiviral activity when added to infected ASK cells

Abstract

Infectioussalmonanemiavirus(ISAV)hascausedgreatlossestotheChileansalmonindustry,andthesuccessofpreventionandtreatmentstrategiesisuncertain.TheuseofRNAinterference(RNAi)isapromisingapproachbecauseduringthereplicationcycle,theISAVgenomemustbetranscribedtomRNAinthecytoplasm.WeexploredthecapacityofE.colitransformedwithplasmidsthatproducedouble-strandedRNA(dsRNA)toinduceantiviralactivitywhenaddedtoinfectedASKcells.Wetransformedthenon-pathogenicEscherichiacoliHT115(DE3)withplasmidsthatexpressedhighlyconservedregionsoftheISAVgenesencodingthenucleoprotein(NP),fusion(F),hemagglutinin(HE),andmatrix(M)proteinsasdsRNA,whichistheprecursoroftheRNAimechanism.TheinactivatedtransformedbacteriacarryingdsRNAweretestedfortheircapacitytosilencethetargetISAVgenes,andthedsRNAthatwereabletoinhibitgeneexpressionweresubsequentlytestedfortheirabilitytoattenuatethecytopathiceffect(CPE)andreducetheviralload.Ofthefourtargetgenestested,inactivatedE.colitransformedwithplasmidsproducingdsRNAtargetingHEshowedantiviralactivitywhenaddedtoinfectedASKcells.