[Immunosuppressant dexamethasone can significantly extend the expression of hepatitis B virus antigens in the HBV mouse model by hydrodynamic transfection method].

To develop a HBV infection mouse model by hydrodynamic-based transfection and further to optimize the method of development of HBV infection mouse model. We first developed a construct which contained inverted terminal repeat elements (ITR) of adeno-associated virus (AAV) and 1. 3 copies of HBV genome (ayw subtype). The pAAV-HBV1. 3 DNA was then injected hydrodynamically into the tail veins of C57BL/6 mice in 5 seconds. The virus load in serum and liver was assayed by ELISA and Real-time PCR. The expression of virus antigen and the pathologic changes of liver were analyzed by HE and immunohistochemical staining. Meanwhile, to develop HBV transfected immunosuppressied mouse, mice were injected intraperitoneally triple with 0.2 ml dexamethason (50 mg/kg) every two days before HBV transfection. The levels of HBsAg and HBeAg were assayed by ELISA. Our data showed: (1) HBsAg and HBeAg were positive (100%) in serum and liver of experimental normal mouse at day 10 after HBV transfection, and became negative at day 30 and day 60. Meanwhile the viral load in serum and liver in experimental group was significantly higher than that in control group at day 10, 30 and 60 after HBV transfection (P < 0.01, P < 0.05, respectively). (2) HBsAg and HBeAg in serum in immunosuppressed mouse model were positive until 60 days. In conclusion, a HBV infection mouse model was developed successfully by hydrodynamic-based transfection. By suppressing the immune status of mice injected with dexamethasone, the expression of HBV antigens was extended longer than that in normal adult mice. These models pave a way for HBV research and evaluation of HBV vaccine and drug development.