To identify the mechanisms of viral persistence in coincides with the cessation of hepatocyte injury. 1,2 Howpatients with chronic hepatitis B after the acquisition ever, with current molecular biological techniques, trace of anti -hepatitis B surface antigen antibodies (anticoncentrations of HBV DNA have been detected by poly-HBs), we serially analyzed the nucleotide sequence of merase chain reaction (PCR) amplification assays in sethe envelope region in a cohort of infected patients. rum, liver, and peripheral blood mononuclear cells from Four patients with histological diagnoses of chronic HBsAg-negative individuals, both in the presence and hepatitis B who had at least 5 years of observance by absence of circulating anti-hepatitis B surface antigen our hospital staff were studied. All but one showed norantibodies (anti-HBs). [3][4][5][6] Recently, an HBV DNA se-
malization of serum alanine aminotransferase (ALT)
quence study in HBsAg-negative patients revealed that concentration after clearance of the hepatitis B surface antigen (HBsAg) and the appearance of anti-HBs. Hepa-numerous mutations had occurred in the envelope retitis B virus (HBV) DNA was still detectable by polymergion. [7][8][9] One report suggested that mutations in the prease chain reaction (PCR) amplification assay in serum S and/or S region may contribute to viral escape from specimens from two patients, even in the presence of the immune pressure of anti-HBs. 10 Although some mucirculating anti-HBs. The envelope gene was amplified tations in the envelope gene may facilitate low-level viby PCR in serum samples obtained both before and ral replication, 9 the clinical significance of undetectable after seroconversion, and direct cycle sequencing of the serum HBV DNA from HBsAg-negative patients is still PCR products was performed. A mutation resulting in unknown. However, a previous study has demonstrated a premature stop codon was found in the pre-S1 region of one patient just prior to clearance of HBsAg. Two that some chronic hepatitis B patients who had cleared years later, the stop codon was converted to a leucine HBsAg still developed cirrhosis and hepatocellular carcodon and three mutations developed in the ''a'' loop. cinoma. 11 Therefore, the presence of HBV DNA despite In the other patient, 16 amino acids had been deleted anti-HBs may portend the risk of subsequent, severe between amino acids 8 and 23 in the pre-S2 region be-HBV-related liver disease. To further identify strategies fore clearance of HBsAg. After the appearance of circuof viral persistence in patients with chronic hepatitis B lating anti-HBs, the pre-S2 gene reverted to wild type Abbreviations: HBV, hepatitis B virus; HBsAg, hepatitis B virus surface B e antigen (HBeAg), and HBV DNA. Histological examinaantigen; PCR, polymerase chain reaction; anti-HBs, anti-hepatitis B surface tion of liver biopsy specimens confirmed the presence of antigen; HBeAg, hepatitis B e antigen; anti-HBe, antibody to hepatitis B e chronic hepatitis B. No patient had been treated with corticoantigen; anti-HBc, antibody to hepatitis B core antigen; OD, optimal density; steroids, immunostimulants, immunosuppressive agents, in-ALT, alanine transaminase.