Objective      To investigate the efficiency difference between lipofection and electroporation for HBV X gene transfection and the effects of HBV X protein (HBx) on CIITA and HLA-DR expression in human liver cell line L02.       Methods      Recombinant expression plasmid pHBx-IRES2-EGFP was constructed and transferred into normal human liver cell line L02 with Lipofectamine 2000 and electroporation respectively. The transfection efficiency was evaluated by the expression of enhanced green fluorescent protein (EGFP) under a fluorescent microscope. Flow cytometry was used to detect HBx protein expression. RT-PCR

flow cytometry and Western blot analysis were used to determine HLA-DR and CIITA expression in L02 cells

L02 cells transfected with pIRES2-EGFP

and L02 cells transfected with pHBx-IRES2-EGFP respectively.       Results      The transfection efficiency with Lipofectamine 2000 was (6.4±3.5)%

significantly lower than that with electroporation [(41.46±5.8)%

P0.01]. The HBx expression in the L02 cells transfected by Lipofectamine 2000 was significantly lower than that in the L02 cells transfected by electroporation [(5.1±3.9)% vs (37.5±4.1)%

P0.01]. The CIITA and HLA-DR expression was only detected in the L02 cells transfected with pHBx-IRES2-EGFP.       Conclusion      Using recombinant expression plasmid pHBx-IRES2-EGFP

HBV X gene transfection mediated by electroporation achieves a higher efficiency and a higher HBx expression level in L02 cell lines than that mediated by Lipofectamine 2000. HBx induces CIITA and HLA-DR expression in L02 cells.