AIM:RNA interference(RNAi)is a newly discoveredphenomenon provoked by dsRNA.The dsRNA is initiallycleaved by Dicer into 21-23 nt small interfering RNA(siRNA)and can then specifically target homologous mRNA fordegradation by cellular ribonucleases.RNAi has beensuccessfully utilized to down-regulate the endogenous geneexpression or suppress the replication of various pathogensin mammalian cells.In this study,we investigated whethervector-based siRNA promoted by U6(pSilencer1.0-U6)could efficiently inhibit HBV replication in cell culture.METHODS:pSilencer vectors with inserts targeting ondifferent regions of HBV genome were constructed.Theseplasmids were co-transfected with pHBV3.8 into Huh-7 cellsvia lipofection and viral antigens were measured by ELISA.Viral RNA was analyzed by Northern blot.The mRNA ofMxA and 2’-5’OAS was reverse transcribed and quantifiedby real-time PCR.RESULTS:Vector-based siRNA could potently reducehepatitis B virus antigen expression in transient replicativecell culture.Furthermore,Northern blot analysis showedthat viral RNA was effectively degraded,thus eliminatingthe messengers for protein expression as well as templatefor reverse transcription.Real-time PCR analysis of cellularMxA and 2’-5’OAS gene expression revealed that vector-based siRNA did not provoke the interferon pathway whichreassured the specificity of the vector-based RNAinterference technique.CONCLUSION:Our results indicate that RNA interferencemay be a potential tool to control HBV infection. AIM: RNA interference (RNAi) is a newly discovered phenomenon induced by dsRNA. DsRNA is initiallycleaved by Dicer into 21-23 nt small interfering RNA (siRNA) and can then specifically target homologous mRNA fordegradation by cellular ribonucleases. RNAi has been fully utilized to down -regulate the endogenous gene expression or suppress the replication of various pathogens in mammalian cells. In this study, we investigated whethervector-based siRNA promoted by U6 (pSilencer1.0-U6) could not inhibit HBV replication in cell culture. METHODS: pSilencer vectors with inserts targeting on different regions of HBV genome were constructed.These plasmids were co-transfected with pHBV3.8 into Huh-7 cellsvia lipofection and viral antigens were measured by ELISA. Viral RNA was analyzed by Northern blot.The mRNA ofMxA and 2’-5’OAS was reverse transcribed and quantified by real-time PCR .RESULTS: Vector-based siRNA could potently reduce hepatitis B virus antigen expression in transient replicative cell c ulture. Stillrther, Northern blot analysis showed that viral RNA was effectively degraded, thus eliminating the messengers for protein expression as well as template for reverse transcription. Real-time PCR analysis of cellular MxA and 2’-5’OAS gene expression revealed that vector-based siRNA did not provoke the interferon pathway whichreassured the specificity of the vector-based RNA interference technique. CONCLUSION: Our results indicate that RNA interferencemay be a potential tool to control HBV infection.