| Hepatitis B Virus (HBV) has been identified as a major cause of infectioushepatitis. It has been shown that searching effective anti-HBV drugs is an urgent workin China, for HBV infection is the major epidemic disease in China. Studies onanti-HBV monoclonal antibodies, vaccines and drugs require a suitable tissue culturesystem. This has prompted many different attempts to establish an in vitro system forpropagation of HBV. The tissue culture systems in practical use are primary duckhepatocytes infected with duck hepatitis B virus (DHBV) and permanent hepatomacell lines transfected by HBV DNA. Such models do not mimic normal adult humanhepatocytes since they originated either from nonhuman species or from transformedcells, which have generally undergone genetic and metabolic changes. And thenpharmacologic study results using above models may be not so accurate. Analternative experimental approach, which most closely mimic the in vivo process ofviral infection, is needed.Here, we describe an in vitro system for infection with HBV that uses adulthuman liver cells and hepatoma cell lines. In vitro experimental infection of thesecells results de novo synthesis of viral protein and DNA. These cells are susceptible toviral replication as shown by (1) de novo production of viral protein: HBsAg andHBeAg; (2) appearance of HBV DNAp in supernatant of hepatoma cell; (3)appearance of single-stranded HBV DNA, cccDNA, RC DNA(replicative DNAintermediates) in the cytoplasm of infected cells.It showed that the production of HBsAg was always more active than that ofHBeAg. It was paralleled by the results obtained from others. After the detection ofviral proteins, proteins in the medium decrease down gradually, but maintainedpositive for 2 weeks. With increasing time in tissue culture, cells gradually lost thecapability for prAuction of viral proteins. To improve the functional stability ofhuman hepatocytes, we add DM50 into the culture medium. It has been shown thatthis composition is beneficial in the prAuction for viral prAucts in tissue culture.When infected hepatoma cells, we selected several factors to promote the infectionefficiency. It shown that viral protein achieve high level at the condition ofdexamethasone and insulin as simulation factor, 10% HBV positive serum and HepG2cell as host cell. We compare the results between the infected HepG2 andHepG2.22 15. It shown that viral protein express level in HepG2 is lower than that ofHepG2.22 15. but it remains positive. Southern blotting analysis reveal that thecytoplasmic HBV DNA in both cells is the same, but the host cell chromosome DNAshow the difference: in HepG2.22 15 the result is positive, in the infected HepG2 it isnegative. Such results indicate that the HBV in infected HepG2 replicate as episomalpattern. When transfected cell line HepG2.22 15 was established, the HBV DNA wastransfeeted into the host chromosome DNA and thus it can secrete viral proteins andHBV DNA, but the system described here was established by the infection ability ofHBV particle.The advantage of this mAel over transfected systems is that the HBV life cycle iscloser to its nature cycle and thus is more suitable for valuation of neutralizing6anti-HBV monoclonal antibodies and antiviral drugs. The advantage can be observedin pharfnachology use.We check the effect of SCs , PD and AP, MPA in HepG2.2215, and SCs and PDshow the certain anti-HBV effect, we did not observe effect of AP and MPA on HBVreplication. However, AP and MPA show anti-HBV effect in HepG2 cell infectedwith HBV. The effect of MPA and AP on HBV replication can not be observed intransfected cell HepG2.22 15, it indicated that the replication pattern of HBV in twosystem is different, in transfected HepG2.2215 it is chorosomal pattern, in infected...
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