AIM:To investigate the effects of hepatitis B virus×geneand its protein product HB×Ag on apoptosis in hepatocyteline HL-7702.METHODS:The reconstituted plasmid pcDNA3-x wasestablished through recombination DNA technique;pcDNA3-X was transfected into HL-7702 cells by lipid-mediatedtrasfection.Positive clones were screened by G418,and HL-7702/HBx cells were analysed by the RT-PCR to confirm thesteady expression of X gene in HL-7702 cells.The apoptosisrate in HL-7702 cells was determined by flow cytometry,TUNEL technology,electronic microscope.At the mean time,pcDNA3-X was transfected transiently into HL-7702 cells,and total RNA from HL-7702 cells was extracted 24,48,72,96 and 120 h after the transient transfection,and semi-quantitative analysis was performed by RT-PCR to detectthe expression of HBV X gene.Furthermore,apoptosis ratein HL-7702 cells was determined by flow cytometry analysisat the different times.RESULTS:RT-PCR analysis showed that HBV X gene couldbe expressed stably in HL-7702 cells.Both flow cytometryand TUNEL technology revealed that the apoptosis rates ofHL-7702/HBx cells were much higher than those of HL-7702/pcDNA3 and HL-7702 cells.Furthermore,the apoptoticphenomena and apoptotic body were observed in HL-7702/HBx cells under electronic microscope,but not in HL-7702/pcDNA3 and HL-7702 cells.In the experiment of transienttransfection,RT-PCR reveals that X gene was expressed mostat 72 h after transfection;and the apoptosis rate reachedthe highest at the same time.After that,the apoptosis ratewas reduced with the decrease of the X gene expression.CONCLUSION:HBV X gene and X protein can promote theapoptosis in hepatocyte.And there exist a quantity-effectrelationship between the X gene expression and apoptosisrate in hepatocyte. AIM: To investigate the effects of hepatitis B virus × gene and its protein product HB × Ag on apoptosis in hepatocyteline HL-7702.METHODS: The transfected recombinant plasmid pcDNA3-x wasestablished through recombination DNA technique; pcDNA3-X was transfected into HL-7702 cells by lipid-mediatedtrasfection. Positive clones were screened by G418, and HL-7702 / HBx cells were analyzed by the RT-PCR to confirm thesteady expression of X gene in HL-7702 cells. The apoptosisrate in HL-7702 cells was determined by flow cytometry, TUNEL technology, electronic microscope. At the time, pcDNA3-X was transfected into HL-7702 cells, and total RNA from HL-7702 cells was extracted 24, 48, 72, 96 and 120 h after the transient transfection, and semi-quantitative analysis was performed by RT-PCR to detect the expression of HBV X gene.Furthermore, apoptosis rate in HL-7702 cells was determined by flow cytometry analysisat the different times .RESULTS: RT-PCR analysis showed that HBV X gene could be expressed stably in HL -7702 cells.Both flow cytometry and TUNEL technology revealed that the apoptosis rates of HL-7702 / HBx cells were much higher than those of HL-7702 / pcDNA3 and HL-7702 cells. Frthermore, the apoptoticphenomena and apoptotic body were observed in HL-7702 / HBx cells under electronic microscope, but not in HL-7702 / pcDNA3 and HL-7702 cells. In the experiment of transient transfection, RT-PCR reveals that X gene was expressed mostat 72 h after transfection; and the apoptosis rate reached the highest at the the same time. After that, the apoptosis rate was reduced with the decrease of the X gene expression. CONCLUSION: HBV X gene and X protein can promote theapoptosis in hepatocyte. There is a quantity-effect relationship between the X gene expression and apoptosisrate in hepatocyte.