title: Evidence of serologic activity in chronic hepatitis B after surface antigen (HBsAg) seroclearance documented by conventional HBsAg assay.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: Wai-Kay
authors.initials: WK
authors.lastname: Seto
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Danny Ka-Ho
authors.initials: DK
authors.lastname: Wong
authors.forename: Ching-Lung
authors.initials: CL
authors.lastname: Lai
authors.forename: Noboru
authors.initials: N
authors.lastname: Shinkai
authors.forename: John Chi-Hang
authors.initials: JC
authors.lastname: Yuen
authors.forename: Teresa
authors.initials: T
authors.lastname: Tong
authors.forename: James
authors.initials: J
authors.lastname: Fung
authors.forename: Ivan Fan-Ngai
authors.initials: IF
authors.lastname: Hung
authors.forename: Man-Fung
authors.initials: MF
authors.lastname: Yuen
keywords: HBcrAg; HBsAg; Linearized HBsAg; Seroclearance; Serology