Abstract
BackgroundThe 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.Methodology/Principal FindingsHBsAg 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 log10 IU/mL; −0.57 to 0.64, −0.04 log10 IU/mL; −0.09 to 0.45, −0.27 log10 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).Conclusion/SignificanceThe 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.
Highlights
There has been recent renewed interest in measuring serum levels of hepatitis B virus surface antigen (HBsAg) as a surrogate marker to predict HBsAg loss and monitor anti-Hepatitis B virus (HBV) therapy
HBsAg quantitation obtained with Diasorin vs. Roche assays presented acceptable mean differences (0.32 log10 IU/mL,) and strong correlation (r = 0.82, p,0.0001), likewise for Bio-Rad versus Roche and Diasorin vs. Bio-Rad
Among the several assays quantifying HBsAg that are commercially available in Europe - Elecsys II (Roche Diagnostics), ADVIA Centaur HBsAg assay (Bayer), Hepanostika HBsAg (Biomerieux) [23] - the Architect assay has been the most frequently cited in published studies
Summary
There has been recent renewed interest in measuring serum levels of HBsAg as a surrogate marker to predict HBsAg loss and monitor anti-HBV therapy. HBV therapy can induce a complete loss of HBsAg indicating the control of chronic infection in some patients. HBsAg clearance was reported in 3% of HBeAg positive patients after one year of treatment with lamivudine [4] and in 5% after 5 years treatment with adevovir [5]. These results should be compared with the 0.5 to 1% annual frequency of HBsAg clearance natural occurring in untreated HBV chronic infection [6,7,8,9,10]. The HBsAg levels obtained by different immunoassays need comparing and the relationships between levels of HBsAg and HBV DNA alongside HBsAg and genotype must be evaluated
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