A polymerase chain reaction（PCR）-based siRNA expression strategy was employed to rapidly screen for effective siRNA sequences.Two effective siRNAs sequences（designated as S2 and X1） which reduced the HBV RNA by >90% were identified.For delivering the siRNAs

they were cloned into a human foamy virus（HFV） based vector to generate single siRNA expression vectors HFVU6-siS2

HFVU6-siX1 and a dual siRNA expression vector HFVU6-siSX.After indrodcing the siRNAs into HepAD38 cell lines

the expression level of HBV genes and the replications of HBV were analyzed by ELISA

Western blot

Quantitative PCR analysis

RT-PCR and Southern blot.It was identified that these siRNA vectors can effectively inhibit multiple HBV gene expression and viral DNA replication.In addition

the repression of HBV RNA and DNA was stable up to 3 months post-transduction.