title: Characterization of hepatitis B virus genotypes and quantitative hepatitis B surface antigen titres in North American tertiary referral liver centres.
abstract: OBJECTIVE
  Hepatitis B virus (HBV) genotype and quantitative hepatitis B surface antigen (qHBsAg) have been related to clinical outcome. In this nationwide cross-sectional study, we aimed to investigate the epidemiology and clinical significance of HBV genotype and qHBsAg in patients with chronic hepatitis B (CHB).
  
  
  METHODS
  Six hundred and thirty patients with CHB were seen in four urban tertiary referral centres in Canada. HBV genotype was determined by line probe assay (INNO-LIPA) and HBV DNA quantified by commercial PCR (Roche TaqMan, sensitivity <55 IU/ml or AMPLICOR, sensitivity <60 IU/ml). Titres of qHBsAg were determined by an in-house assay based on the WHO standard (calibration range 0.24-62.5 IU/ml).
  
  
  RESULTS
  In 630 patients (57% male, 69% Asian, median age 42 years), 21% were hepatitis B e antigen positive and the median alanine aminotransferase was 29 U/L. The HBV genotype distribution was A (16%), B (29%), C (31%), D (16%), E (6%). HBV genotype was strongly associated with ethnicity, but neither genotype nor qHBsAg correlated with the degree of fibrosis. In the treatment-naïve patients, the baseline qHBsAg levels correlated with HBV DNA (r = 0.2517, P < 0.0008). The median qHBsAg levels were lowest in patients with genotype B (P < 0.0001), but no significant correlation was noted with all other HBV genotypes.
  
  
  CONCLUSIONS
  In this large North American HBV epidemiological study, genotypes B and C were the most common; however, all genotypes (A-E) were observed with varied distribution nationwide. Baseline qHBsAg significantly correlated with HBV DNA and with HBV genotype B, but not with liver fibrosis.
authors.affiliation: Liver Unit, Division of Gastroenterology and Hepatology, University of Calgary, Calgary, AB, Canada.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Congly
authors.forename: Philip
authors.initials: P
authors.lastname: Wong
authors.forename: Said A
authors.initials: SA
authors.lastname: Al-Busafi
authors.forename: Karen
authors.initials: K
authors.lastname: Doucette
authors.forename: Scott K
authors.initials: SK
authors.lastname: Fung
authors.forename: Peter
authors.initials: P
authors.lastname: Ghali
authors.forename: Kevin
authors.initials: K
authors.lastname: Fonseca
authors.forename: Robert P
authors.initials: RP
authors.lastname: Myers
authors.forename: Carla
authors.initials: C
authors.lastname: Osiowy
authors.forename: Carla S
authors.initials: CS
authors.lastname: Coffin
mesh_terms: D000328:Adult; D000410:Alanine Transaminase / Q000097:blood; D000704:Analysis of Variance; D002170:Canada / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000453:epidemiology* / Q000473:pathology / Q000821:virology; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity
chemical_list: D006514:Hepatitis B Surface Antigens; D000410:Alanine Transaminase
keywords: Canada; HBV DNA; HBV genotype; chronic hepatitis B; quantitative hepatitis B surface antigen