Coexistence of hepatitis B virus quasispecies enhances viral replication and the ability to induce host antibody and cellular immune responses.
Hepatitis B virus (HBV) quasispecies contain a large number of variants that serve as a reservoir for viral selection under antiviral treatment and the immune response, leading to the acute exacerbation and subsequent development of liver failure. However, there is no clear experimental evidence for a significant role of HBV quasispecies in viral pathogenesis. In the present study, HBV sequences were amplified from a patient with severe liver disease and used for construction of HBV replication-competent plasmids. Western blotting, enzyme-linked immunosorbent assay (ELISA), and immunofluorescence staining were performed to analyze the expression, secretion, and subcellular localization of viral proteins in vitro. Viral replication intermediates were detected by Southern blotting. HBV gene expression and replication and the induction of specific immune responses in an HBV hydrodynamic injection (HI) mouse model were investigated. The results demonstrated that two naturally occurring HBV variants, SH and SH-DPS, were identified. The variant SH-DPS expressed only a nonexportable hepatitis B virus surface antigen (HBsAg) with abnormal intracellular accumulation. The coexistence of the HBV variants at a ratio of 1 to 4 (SH to SH-DPS) increased HBV replication. Significantly stronger intrahepatic cytotoxic T lymphocyte (CTL) responses and antibody responses specific to HBsAg were induced in mice by the HBV variants when coapplied by HI. These findings uncovered an unexpected aspect of HBV quasispecies: the coexistence of different variants can significantly modulate specific host immune responses, representing a novel mechanism for the immunopathogenesis of HBV infection.


OBJECTIVE
Hepatitis B virus (HBV) is an important human pathogen. HBV quasispecies with genetically heterogenous variants are thought to play a role in the progression of HBV-associated liver diseases. So far, direct evidence is available in only a few cases to confirm the proposed role of HBV variants in the pathogenesis. We report here that the coexistence of two naturally occurring HBV variants at a ratio of 1 to 4 increased HBV replication and induced significantly stronger intrahepatic cytotoxic T lymphocyte responses and antibody responses specific to HBV surface antigen (HBsAg) in mice. Our discovery uncovered an unexpected aspect of HBV quasispecies: the coexistence of different variants can significantly modulate specific host immune responses and may enhance immune-mediated liver damage under some circumstances, representing a novel mechanism for the immunopathogenesis of HBV infection.
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China University of Chinese Academy of Sciences, Beijing, China.
Liang
L
Cao
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China wucc@wh.iov.cn chenxw@wh.iov.cn.
Chunchen
C
Wu
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
Hui
H
Shi
Department of Infectious Diseases, Renmin Hospital of Wuhan University, Wuhan, China.
Zuojiong
Z
Gong
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
Ejuan
E
Zhang
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China University of Chinese Academy of Sciences, Beijing, China.
Hui
H
Wang
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China University of Chinese Academy of Sciences, Beijing, China.
Kaitao
K
Zhao
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China University of Chinese Academy of Sciences, Beijing, China.
Shuhui
S
Liu
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
Songxia
S
Li
Department of Hepatology, First Hospital of Jilin University, Changchun, China.
Xiuzhu
X
Gao
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
Yun
Y
Wang
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
Rongjuan
R
Pei
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China Institute of Virology, University Hospital of Essen, Essen, Germany Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Mengji
M
Lu
State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China wucc@wh.iov.cn chenxw@wh.iov.cn.
Xinwen
X
Chen
D000328:Adult; D000818:Animals; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D004195:Disease Models, Animal; D014644:Genetic Variation; D006509:Hepatitis B / Q000276:immunology / Q000821:virology*; D006510:Hepatitis B Antibodies / Q000097:blood*; D006515:Hepatitis B virus / Q000145:classification / Q000235:genetics / Q000276:immunology* / Q000502:physiology*; D006801:Humans; D007111:Immunity, Cellular; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D014779:Virus Replication
D004279:DNA, Viral; D006510:Hepatitis B Antibodies