Evidence of serologic activity in chronic hepatitis B after surface antigen (HBsAg) seroclearance documented by conventional HBsAg assay

BACKGROUND Possible serologic activity after hepatitis B surface antigen (HBsAg) seroclearance documented by conventional assays in chronic hepatitis B (CHB) has not been thoroughly investigated. METHODS We determined the levels of serum hepatitis B virus (HBV) DNA, hepatitis B core-related antigen (HBcrAg), and linearized HBsAg (CLEIA prototype) in 329 CHB patients (72.0% male) after HBsAg seroclearance was documented by a conventional HBsAg assay. RESULTS The median interval between presentation and HBsAg seroclearance was 69.4 months. The median age at HBsAg seroclearance was 50 years. Assays for serum HBV DNA, HBcrAg, and linearized HBsAg were performed at a median time interval of 11.2 months after HBsAg loss. Linearized HBsAg and HBcrAg were detectable in 85 (25.8%) and 69 (21%) patients, respectively, and one or both serologic markers were detectable in 133 patients (40.4%). Serum HBV DNA was detectable in only 7 patients (2.1%). There was no correlation between linearized HBsAg and HBcrAg levels (r = 0.095, p = 0.924). The incidences of detectable linearized HBsAg and HBcrAg did not differ between patient samples taken at 6-12 and >12 months after HBsAg seroclearance (p = 0.146 and 0.079, respectively). Among patients with detectable serologic markers, median levels of linearized HBsAg (p = 0.581) and HBcrAg (p = 0.951) did not significantly change with time after HBsAg seroclearance. CONCLUSION Using novel HBcrAg and linearized HBsAg assays, viral serologic activity after HBsAg seroclearance was demonstrated in more than 40% of CHB patients. These tests have potential applications in diagnosing and prognosticating CHB patients with HBsAg seroclearance.