Hepatitis C virus (HCV) non structure 3 (NS3) protein and hepatitis B virus (HBV) X protein expressing plasmids were constructed with the vector pcDNA3 1(-). The plasmids were transfected into HepG2 cells and the viral proteins expressed in HepG2 cells were identified using Western blotting methods. Then the two recombined plasmids were transfected into HepG2 cells and were cotransfected into HepG2 cells with reporter plasmid pCAT3 promoter. The activity of CAT enzyme was detected by a CAT ELISA assay kit, which reflected the transactivating function of two proteins on SV40 early promoter. The findings indicated that the expression of two viral proteins were successfully detected in soluble protein cell extracts of transiently transfected HepG2 cells. HCV NS3 protein transactivated the CAT enzyme expressed at a value 3 5 fold higher than the control, while HBX protein transactivated at a value 4 4 times. It arrived at 8 5 times when transfected with two plamids simultaneously. The activating effect was increased in relation to the amount of plasmids. It was suggested that the two kinds of viral proteins had a transactivating effect on SV40 early promoter, and they acted synergistically. These results might contribute to explaining the mechanisms of liver injury or tumorigenesis induced by HCV or/and HBV infection

Hepatitis C virus (HCV) non structure 3 (NS3) gene was amplified from plasmid pBRTM3011 by employing polymerase chain reaction (PCR), and the amplified product was cloned into pcDNA3 1(-) vector. Then the recombinant plasmid pcDNA3 1(-) NS3 was transfected into HepG2 cells and was cotransfected into HepG2 cells with reporter plasmid pCAT3 promoter, respectively. HCV NS3 protein expressed in HepG2 cells was detected by reverse transcription PCR (RT PCR) and Western blotting method. The activity of CAT was detected by a ELISA kit, which reflected the transactivating function of HCV NS3 protein. The results showed that HepG2 cells transfected with pcDNA3 1(-) NS3 could express HCV NS3 protein. The expression of CAT in HepG2 cells transfected with the pcDNA3 1(-) NS3 was 4 6 fold higher than that of control plasmid. It was suggested that the recombinant plasmid pcDNA3 1(-) NS3 could be expressed in mammalian cell line, and had transactivating effect on SV40 early promoter