Objective:Toconstructarecombinantplasmidcontainingtheoutermembraneprotein2(Omp2)geneofChlamydiatrachomatisandexpressOmp2inE.coli.Methods:Theomp2geneofC.trachomatisserovarDwasclonedintopQE30vectorfollowingPCRamplificationfromgenomicDNA.E.coliM15transformantswereinducedtoexpressthefusionproteinbyIPTGandtheproductwasidentifiedbySDS-PAGEandWesternblot.Results:ConfirmedbyenzymecleavageanalysisandDNAsequencing,acorrectrecombinantplasmidpQE30/omp2wasconstructed.Thefusionproteinfromthetransformantswasapproximately60kDainsizeinSDS-PAGEanalysis,whichcouldspeciallyreactwithanti-6×HismousemonoclonalIgGantibodies.Conclusion:WesuccessfullyexpressedOmp2inE.coilM15,providinganefficientandsimplesystemforassayingtheimmunologicalpropertiesofOmp2.