Chronic hepatitis B (CHB) is a serious liver disease worldwide, and the leading cause of cirrhosis and hepatocellular carcinoma (HCC). HBsAg loss/seroconversion is considered to be the ideal endpoint of antiviral therapy in both HBeAg-positive and -negative patients, and the ultimate treatment goal in CHB, However HBsAg loss occurred rarely by interferon treatment. Although It was reported that in nature history HBsAg level≤100 IU/ml can bring good long term outcomes in patients with chronic hepatitis B. it was not clear whether patients who achieved HBsAg level≤100 IU/ml by interferon treatment could maintain sustained viral response and the state of HBsAg level≤100 IU/ml.

The patients with chronic hepatitis B and achieved HBsAg level≤100 IU/ml after completed interferon treatment will be enrolled and observed for 96 weeks. Serum HBV DNA, HBsAg, anti-HBs, HBeAg, and anti-HBe will be measured every 3 months during the observation period, liver function tests were performed every 3 months also. The liver ultrasonic examination would be taken every 3-6 months. The primary endpoint is HBV DNA reaction. The secondary endpoints is HBsAg loss.

Inclusion Criteria:

• patients who had chronic hepatitis B and achieved HBsAg level≤100 IU/ml with undetectable HBV DNA level by interferon treatment

Exclusion Criteria:

• Active consumption of alcohol and/or drugs
• Co-infection with human immunodeficiency virus, hepatitis C virus, or hepatitis D virus
• History of autoimmune hepatitis
• Psychiatric disease
• Evidence of neoplastic diseases of the liver

the study population in this study were composed of patients who had chronic hepatitis B and achieved HBsAg level≤100 IU/ml with undetectable HBV DNA level after interferon treatment, and serum HBsAg and HBV DNA would be tested every 3 months for 96 weeks after finished treatment. Sustained viral response defined as serum HBV DNA maintaining undetectable during the observation period. HBsAg loss is defined as HBsAg level reached the value lower than the low limited value.