What can be revealed by extending the sensitivity of HBsAg detection to below the present limit?☆

Background/Aims

We investigated what can be revealed by extending the sensitivity of HBsAg detection to below the present limit.

Methods

We examined the sensitivity of this immunoassay in comparison with real-time PCR detection of HBV DNA using serially diluted sera from HBV carriers. Low HBsAg was measured in 210 healthy volunteers and 368 patients with non-B chronic liver diseases who were negative for HBsAg by a standard EIA method.

Results

The radical immunoassay was able to detect HBsAg at a concentration of 0.025ng/ml. Low HBsAg was positive in 6 of 210 normal volunteers (2.86%), 5 of 65 non-B, non-C cirrhosis patients (7.69%), 6 of 62 non-B, non-C hepatocellular carcinoma patients (9.68%: p=0.04 vs. volunteers), 12 of 134 chronic hepatitis C patients (8.96%: p<0.02 vs. volunteers), and 11 of 107 hepatocellular carcinoma patients complicated by chronic hepatitis C (10.28%: p<0.008 vs. volunteers). Although no HBV DNA was positive in healthy volunteers, 9 patients with non-B chronic liver diseases were positive for HBV DNA by real-time PCR analysis.

Conclusions

Increasing the sensitivity of HBsAg detection to below the present limit has revealed that infection with HBV, including occult HBV, is far more endemic than suspected previously.

Abbreviations: DMSO, dimethyl sulfoxide, ESR, electron spin resonance, HBV, hepatitis B virus, HBsAg, hepatitis surface antigen, HCC, hepatocellular carcinoma, HTIO, 1-hydroxy-2,2,5,5-tetramethyl-3-imidazoline-3-oxide, MOPS, 3-morpholinopropanesulfonic acid, p-AP, p-acetamidophenol, PCR, polymerase chain reaction, S/N, signal to noise

Keywords: Electron spin resonance, Non-B chronic liver diseases, Occult HBV, Radical immunoassay, Real-time PCR, Clinical research