J Viral Hepat. 2020 Apr 26. doi: 10.1111/jvh.13309. [Epub ahead of print]
Novel hepatitis B virus surface antigen mutations associated with occult genotype Bhepatitis B virus infection affect HBsAgdetection.
Wang H1,2, Wang M2, Huang J2, Xu R2, Liao Q2, Shan Z2, Zheng Y2, Rong X2, Tang X1, Li T1, Wang W1, Li C1, Fu Y1,2.
Author information
1
Department of Transfusion Medicine, School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou, China.
2
Guangzhou Blood Center, Guangzhou, China.
Abstract
The causative factors of occult hepatitis B infection are complicated and not yet been fully elucidated. Mutations in hepatitis B virus (HBV) S gene are one of the factors may contributing to occult infection. In this study, 89 blood donors with genotype B occult HBV were investigated. Fifty-seven HBsAg positive/HBV DNA positive blood donors served as control group for comparison. Occult HBV related mutations with a high incidence (P<0.05) in the S gene were identified. To further verify theseoccult infection related mutations, a conservative full-gene expression vector of HBV B genotype (pHBV1.3B) was constructed. Then, the mutant plasmids on the basis of pHBV1.3B were constructed and transfected into HepG2 cells. Extracellular as well as intracellular HBsAg were analyzed by Electrochemical luminescence and Cellular Immunohistochemistry. Ten occult infection related mutations (E2G, Q101R, K122R, M133T, D144E, G145R, V168A, S174N, L175S and I226S) were significantly more frequent in the occult infection group (P<0.05). Five of the ten mutations (E2G, D144E, G145R, V168A and S174N) strongly decreased extracellular HBsAg level (P<0.05) in the transfection system. Notably, the E2G mutation had the most significant impact on the ratio of extracellular HBsAg (3.8% vs pHBV1.3B) and intracellular HBsAg (239.3% vs pHBV1.3B) (P<0.05), and the fluorescence density of E2G mutant HBsAg was significantly higher than that of pHBV1.3B (P<0.0001). Hence ten mutations were associated with genotype B occult HBV - E2G and V168A were novel mutations which we confirmed significantly affect HBsAg detection. E2G might cause HBsAg secretion impairment that results in intracellular accumulation and a decrease in HBsAg secretion.
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KEYWORDS:
Hepatitis B virus; HepatitisB surface antigen; Mutation; occult hepatitis B Infection