简介：InFebruary2006,twooutbreaksofhighlypathogenicavianinfluenzaAvirussubtypeH5N1occurredinchickensintwoneighboringdistricts(firstinNandurbarandsecondinJalgaon)ofMaharashtra,India,inaspanof12days.Inthepresentstudy,theneuraminidase(NA)geneofthetwoIndianH5N1isolateswastakenintoconsiderationtofindifthetwostrainsaregeneticallysimilar.PhylogeneticanalysisoftheNAgeneshowedthattheH5N1strainsisolatedfromthetwooutbreakswerenotoriginatedfromthesamesource.ThefirstIndianisolate(Nandubar/7972/06)wasclusteredclosesttoanisolatefromchickeninVietnamin2004,whereasthesecondIndianisolate(Jalgaon/8824/06)showedresemblancetostrainsisolatedfromswaninItalyandIranin2006.Moreover,aminoacidsequenceanalysisshowedvaryinghotspotsforsubstitutionsbetweenthesetwoIndianisolates,andthreesubstitutionswerefoundatfunctionaldomainsites.Secondarystructurechangesduetothesesubstitutionswerealsoreported.ThisstudyrevealsthattheH5N1strainsisolatedfromchickensduring2006birdfluoutbreaksintwoneighboringdistrictsofMaharashtra,Indiaaregeneticallydifferent.