ImmuneresponsesinducedbyaBacMamvirusexpressingtheE2ImmunologyLetters125(2021)145–150ContentslistsavailableatScienceDirectImmunologyLettersjournalhomepage:/locate/ImmuneresponsesinducedbyaBacMamvirusexpressingtheE2proteinofclassicalswinefevervirusinmiceMiaoLi,Yu-FeiWang,YuWang,HuiGao,NaLi,YuanSun,Bing-BingLiang,Hua-JiQiuDivisionofSwineInfectiousDiseases,NationalKeyLaboratoryofVeterinaryBiotechnology,HarbinVeterinaryResearchInstitute,ChineseAcademyofAgriculturalSciences,427MaduanStreet,150001Harbin,Heilongjiang,ChinaarticleinfoabstractNon-replicatingbaculovirus-mediatedgenetransferintomammaliancellshasbeendevelopedasavac-cinestrategyagainstanumberofdiseasesinseveralanimalmodels.Inthepresentstudy,theBacMamvector,abaculoviruspseudotypedwiththeglycoproteinfromvesicularstomatitisvirus,wasusedasarecombinantvectortoexpressclassicalswinefevervirus(CSFV)E2proteinunderthecontroloftheimmediateearly1(ie1)promoterfromshrimpwhitespotsyndromevirus.TheE2genewasefcientlyexpressedinbothinsectandmammaliancells.Intramuscularinjectionofmicewiththerecombinantbaculovirusresultedintheproductionofhigh-titersofCSFV-specicneutralizingantibodies.SpeciclymphoproliferativeresponsestoCSFVstimulationweredetectedinthesplenocytesoftheimmunizedmiceasdemonstratedbyCFSEstainingassayandWST-8assay.ThisstudydemonstratesthattheBacMamvirusvectorcanefcientlyexpresstheE2proteinandeffectivelyinduceimmuneresponsesagainstCSFV.Thisisarststepinthedemonstrationthatthepseudotypedbaculovirus-deliveredCSFVE2genecanbeapotentialnon-replicatingvaccineagainstCSFVinfections.2021ElsevierB.V.Allrightsreserved.Articlehistory:Received23January2021Receivedinrevisedform28June2021Accepted1July2021Availableonline7July2021Keywords:ClassicalswinefevervirusE2geneBacMamvirusRecombinantbaculovirusImmunogenicity1.IntroductionThebaculovirusexpressionsystemhasbeenextensivelyusedasvectorsforabundantexpressionofalargevarietyofforeignproteinsininsectcells.Recently,recombinantbaculovirusvectorscontainingmammaliancell-activepromoterelements(alsoknownasBacMamviruses)havebeenusedsuccessfullyforgenedeliv-eryintomammaliancelllineswithoutapparentviralreplication[1].RecentstudieshavedemonstratedthatBacMamvirusescanbeusednotonlyforefcientgenetransductionintomammaliancellsinvitro[2,3]butalsoforgenetransductioninvivo[4,5].ThemajoradvantageoftheBacMamvirusisthatitshowsefcientgenetransductionintoawidevarietyofcelllinesbydirectinfection.Numerouseffortshavebeenmadetoharnessthebaculovirusasavectorforgenetherapyandvaccinedevelopment.Theuseofbac-ulovirusasavectorforvaccinationwasinitiallydescribedbyAokietal.[6],whodemonstratedthatintramuscularinjectionofmicewitharecombinantbaculovirusexpressingthepseudorabiesvirusgBproteincouldelicitedameasurablehumoralresponse.Further-more,severalgroupshavedemonstratedthatdirectvaccinationwithrecombinantbaculovirusbyintramuscular,intraperitonealorintranasalinoculationcaninducetheproductionofhumoralCorrespondingauthor.Tel.:+8645185935041;fax:+8645185935041.E-mailaddress:huajiqiu@(H.-J.Qiu).0165-2478/$–seefrontmatter2021ElsevierB.V.Allrightsreserved.doi:10.1016/j.imlet.2021.07.001andcell-mediatedimmunityagainstvariousantigens[7–9].Morerecently,Wangetal.[10]reportedthatanimmuneresponsetotheGP5andMproteinsofporcinereproductiveandrespiratorysyn-dromeviruswaseliciteduponvaccinationwithabaculovirusvectorexpressingthevirusstructuralco...