As HBsAg clearance is uncommon in chronic hepatitis B (CHB) patients on nucleoside analogues (NAs) therapy. The purpose of this study is to optimize HBsAg clearance in CHB Patients with sequential treatment of pegylated interferon alpha and NAs.

In order to optimize HBsAg clearance in CHB patients with low level HBsAg, the investigators enrolled patients who had received, and responded to, NAs for more than 12 months(see the inclusion criteria), and patients are switched to receive peginterferon alfa-2a 180 micrograms/week or peginterferon alfa-2b 80 micrograms/week. The longest course of treatment is 96 weeks. After treatment, patients will be followed up for 24 weeks. During the 96 weeks course of treatment, HBsAg level will be monitored. When HBsAg level is less than 0.05 IU/mL, peginterferon treatment will be stopped and patients will receive 24 weeks follow up.

Inclusion Criteria:

1. CHB patients who had received single NAs for more than 12 months.
2. Hepatitis B e antigen (HBeAg)-negative.
3. Hepatitis B surface antigen (HBsAg) positive and <1000 IU/mL.
4. Hepatitis B virus DNA <100 IU/mL.

Exclusion Criteria:

1. Patients with liver cirrhosis, Hepatocellular Carcinoma or AFP >2 ULN or other malignancies.
2. Patients with other factors causing liver diseases.
3. Pregnant and lactating women.
4. Patients with concomitant HIV infection or congenital immune deficiency diseases.
5. Patients with diabetes, autoimmune diseases.
6. Patients with important organ dysfunctions.
7. Patients with serious complications (e.g., infection, hepatic encephalopathy, hepatorenal syndrome, gastrointestinal bleeding.)
8. Patients who receive antineoplastic or immunomodulatory therapy in the past 12 months.
9. Patients with a previous use of IFN anti hepatitis B virus treatment or have NAs drug resistance.
10. Patients who can't come back to clinic for follow-up on schedule.