title: Comparison of serum HBsAg quantitation by four immunoassays, and relationships of HBsAg level with HBV replication and HBV genotypes.
abstract: BACKGROUND
  The decline in hepatitis B virus surface antigen (HBsAg) may be an early predictor of the viral efficacy of Hepatitis B virus (HBV) therapy. The HBsAg levels obtained by different immunoassays now need comparing and the relationships between levels of HBsAg and HBV DNA alongside HBsAg and genotype must be evaluated.
  
  
  RESULTS
  HBsAg levels were compared among 80 patients using the Abbott Architect assay, a commercial immunoassay approved for HBsAg detection and quantitation, and three other assays derived from immunoassays approved for HBsAg detection (manufactured by Diasorin, Bio-Rad and Roche). Good correlation was found between the Abbot vs. Diasorin, Bio-Rad and Roche assays with narrow 95% limits of agreement and small mean differences: -0.06 to 0.11, -0.09 log(10) IU/mL; -0.57 to 0.64, -0.04 log(10) IU/mL; -0.09 to 0.45, -0.27 log(10) IU/mL, respectively. These agreements were not affected by genotypes A or D. HBsAg was weakly correlated with HBV DNA, whatever the HBsAg assay used: Abbott, ρ = 0.36 p = 0.001, Diasorin ρ = 0.34, p = 0.002; Bio-Rad ρ = 0.37, p<0.001; or Roche ρ = 0.41, p<0.001. This relationship between levels of HBsAg and HBV DNA seemed to depend on genotypes. Whereas HBsAg (Abbott assay) tended to correlate with HBV DNA for genotype A (ρ = 0.44, p = 0.02), no such correlation was significant for genotypes D (ρ = 0.29, p = 0.15).
  
  
  CONCLUSIONS
  The quantitation of HBsAg in routine clinical samples is comparable between the reference assay and the adapted assays with acceptable accuracy limits, low levels of variability and minimum discrepancy. While HBsAg quantitation is not affected by HBV genotype, the observed association between levels of HBsAg and HBV DNA seems genotype dependent.
authors.affiliation: Université de Montpellier 1, INSERM Unité 1058, Montpellier, France. e-tuaillon@chu-montpellier.fr
authors.forename: Edouard
authors.initials: E
authors.lastname: Tuaillon
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Mondain
authors.forename: Nicolas
authors.initials: N
authors.lastname: Nagot
authors.forename: Laure
authors.initials: L
authors.lastname: Ottomani
authors.forename: Dramane
authors.initials: D
authors.lastname: Kania
authors.forename: Erika
authors.initials: E
authors.lastname: Nogue
authors.forename: Pierre-Alain
authors.initials: PA
authors.lastname: Rubbo
authors.forename: Georges-Philippe
authors.initials: GP
authors.lastname: Pageaux
authors.forename: Philippe
authors.initials: P
authors.lastname: Van de Perre
authors.forename: Jacques
authors.initials: J
authors.lastname: Ducos
mesh_terms: D000328:Adult; D004279:DNA, Viral / Q000097:blood / Q000235:genetics; D005838:Genotype; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D006513:Hepatitis B e Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D014779:Virus Replication
chemical_list: D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens