The distribution of surface antigen (HBsAg) components can distinguish between inactive carriers and active forms of Hepatitis B virus (HBV) infections

Introduction: Different stages of HBV infections are associated with serum levels of HBV DNA and HBsAg, however, the distinction between active and inactive forms of HBV infections is difficult in many patients. The HBsAg itself consists of the components large (L-), middle (M-) and small (S-) HBsAg. The aim of our study was to investigate the composition of HBsAg during different stages of HBV infections.

Methods: Total HBsAg and HBsAg components were quantified in serum samples of 150 patients (110 male, mean age 46.2 ± 15.4 (17 – 77) years) not receiving antiviral treatment including 41 inactive HBsAg-carriers (mean HBV DNA 3.1 ± 0.7 (range, 1.2 – 3.9 log10 copies/mL), 13 acutely infected patients, 41 with HBeAg negative and 55 patients with HBeAg positive chronic HBV infection (mean age 46.0 ± 15.6 (16 – 78) years) using an ELISA with well-defined monoclonal antibodies for L- and M- and commercial polyclonal antibodies for S-HBsAg/total HBsAg (HBsAg 6.0, Enzgnost, Siemens).

Results: The mean levels of total HBsAg in patients with acute HBV infection were 3.5 ± 1.2 (range, 0.4 – 5.3), in patients with HBeAg negative and HBeAg positive HBV infection 3.6 vs. 4.1 log10 IU/mL (p < 0.001). In comparison to all active forms of HBV infections, inactive carriers had significantly lower mean total HBsAg levels (2.9 ± 1.2 (0.14 – 4.4) vs. 3.8 ± 0.8 (0.4 – 5.5) log10IU/mL; p < 0.001). The ratios of L-, M- and S-HBsAg in acutely infected patients were 9.9%, 9.3% and 80.8%, in HBeAg negative and positive patients 10.3% vs. 12.7% (p = 0.024), 6.5% vs. 5.6% (p = 0.521) and 83.8% vs. 81.7% (p = 0.252), respectively.

In comparison to patients with active HBV infections, mean ratios of HBsAg components in inactive carriers were significantly lower for L- (4.2 ± 2.9 (0 – 11.3) vs. 11.5 ± 5 (1.9 – 25.5)%; p < 0.001, see Figure), higher for S- (92.8 ± 4.3 (80.4 – 100.0)% vs. 83.1 ± 7.4 (60.9 – 93.3); p < 0.001), and lower for M-HBsAg (3.0 ± 3.1(0 – 12.8) vs. 6.4 ± 5.2(0 – 35.5)%; p < 0.001).

Conclusion: Patients with chronic inactive HBV infections show a distinct ratio of HBsAg components when compared to active forms of HBV infections. Quantification of HBsAg components may improve the identification of inactive carriers and individual risk stratification.

Corresponding author: Großmann, Maria

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