Comparison of results of two immunoassays for detection of hepatitis B surface antigen in pregnant women

Objective To evaluate and compare the detection consistency of hepatitis B surface antigen (HBsAg) by two immunoassays: enzyme-linked immunosorbent assay (ELISA) and electrochemiluminescent immunoassay (ECLIA). Methods A prospective study was conducted among 2 296 pregnant women recruited consecutively from January 1, 2014 to January 31, 2015 in a hospital. Blood samples were collected from them for the detection of HBsAg by using ELISA and ECLIA, Kappa test was performed on the results. Nested polymerase chain reaction and sequencing of HBV S gene were also performed in all samples. Phylogenetic analysis was performed using Mega 6.0 software. Results The two methods had high detection consistence of HBsAg (Kappa=0.71). There were significant differences in detection result of B genotype and adw2 serotype HBV strains between two methods. Among 123 identified HBV strains, 113 belonged to genotype B and available for further analysis. The difference in detection of substitution rates between two methods or different positive groups were not significant. Compared with ELISA single positive group, the ECLIA single positive group had completely different substitution sites. Conclusion The two methods had high detection consistence of HBsAg, but there were still 32.4% HBV DNA positive cases in ELISA/ECLIA single positive group, and complete complementary substitution sites between ELISA single positive group and ECLIA single positive group. Our results suggested that more effective detection procedure should be considered for the possible impact of the HBV silent transmission and infection. Key words: Hepatitis B surface antigen; Enzyme-linked immunosorbent assay; Electrical chemiluminescent immunoassay