Patients with chronic hepatitis B infection and relevant liver fibrosis will be treated with entecavir during 5 years or until anti-HBs seroconversion or 6-12 months after anti-HBe seroconversion and HBeAg loss. There are 9 visits during treatment for each patient. At all visits, each patient will consent to give 20 ml blood sample for study examination and 40 ml blood sample for research purposes.