Influence of mutations in hepatitis B virus surface protein on viral antigenicity and phenotype in occult HBV strains from blood donors.
OBJECTIVE
This study aimed at investigating mutations in the hepatitis B surface protein (HBsAg) in occult hepatitis B virus (HBV) infection (OBI) and their influence on viral antigenicity and phenotype.


METHODS
The characteristics of 61 carriers with OBI (OBI group), 153 HBsAg(+) carriers with serum HBsAg ≤ 100 IU/ml (HBsAg-L group) and 54 carriers with serum HBsAg >100 IU/ml (HBsAg-H group) from 38,499 blood donors were investigated. Mutations in the major hydrophilic region (MHR) of the viral sequences were determined. Thirteen representative MHR mutations observed in OBI sequences were antigenically characterized with a panel of monoclonal antibodies (MAbs) and commercial HBsAg immunoassays and functionally characterized in HuH7 cells and hydrodynamically injected mice.


RESULTS
Of 61 OBI sequences, 34 (55.7%) harbored MHR mutations, which was significantly higher than the frequency in either the HBsAg-L (34.0%, p=0.003) or the HBsAg-H group (17.1%, p<0.001). Alterations in antigenicity induced by the 13 representative MHR mutations identified in the OBI group were assessed by reacting recombinant HBV mutants with 30 different MAbs targeting various epitopes. Four out of the 13 mutations (C124R, C124Y, K141E, and D144A) strongly decreased the analytical sensitivity of seven commercial HBsAg immunoassays, and 10 (G119R, C124Y, I126S, Q129R, S136P, C139R, T140I, K141E, D144A, and G145R) significantly impaired virion and/or S protein secretion in both HuH7 cells and mice.


CONCLUSIONS
MHR mutations alter antigenicity and impair virion secretion, both of which may contribute to HBsAg detection failure in individuals with OBI.
National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Life Science, Xiamen University, Xiamen, Fujian Province, China.
Cheng-Hao
CH
Huang
Quan
Q
Yuan
Pei-Jer
PJ
Chen
Ya-Li
YL
Zhang
Chang-Rong
CR
Chen
Qing-Bing
QB
Zheng
Shiou-Hwei
SH
Yeh
Hai
H
Yu
Yu
Y
Xue
Yi-Xin
YX
Chen
Ping-Guo
PG
Liu
Sheng-Xiang
SX
Ge
Jun
J
Zhang
Ning-Shao
NS
Xia
D000293:Adolescent; D000328:Adult; D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived; D002353:Carrier State / Q000821:virology; D045744:Cell Line, Tumor; D004252:DNA Mutational Analysis; D004279:DNA, Viral / Q000097:blood; D005260:Female; D005838:Genotype; D006514:Hepatitis B Surface Antigens / Q000235:genetics* / Q000276:immunology*; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology*; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D009154:Mutation; D010641:Phenotype; D012367:RNA, Viral / Q000096:biosynthesis; D014759:Viral Envelope Proteins / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D014771:Virion / Q000235:genetics / Q000378:metabolism; D055815:Young Adult
D058846:Antibodies, Monoclonal, Murine-Derived; D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D012367:RNA, Viral; C118669:S envelope protein, hepatitis B virus; D014759:Viral Envelope Proteins