Chronic infection with hepatitis B virus (HBV) could lead to liver cirrhosis and hepatocellular carcinoma, which account for 600,000 annual deaths worldwide. Vaccination of the at-risk groups with recombinant small (S) envelope protein can prevent viral infection in the first place, thus averting such devastating health consequences. Unfortunately, breakthrough infection continues to develop in 5 - 10% of infants born to infected mothers despite administration of hepatitis B immune globulin (HBIG) in addition to the vaccine immediately after birth. The responsible HBV isolates often harbor point mutations in the antigenic sites of the S protein suggesting immune escape. Accurate prediction of the threat posed by vaccine escape mutants requires evaluation of their biological fitness. Our preliminary studies revealed impaired virion secretion by many escape mutants, which could nevertheless be rescued by an M133T mutation creating a novel N-linked glycosylation site.
Aim 1 will further validate M133T and others as compensatory mutations that restore the biological fitness of the escape mutants. We will also investigate whether N-linked glycosylation prolongs S protein intracellular trafficking to promote virion formation.
Aim 2 will examine the infectivity of vaccin escape mutants in a human hepatoma cell line reconstituted with the newly discovered high-affinity HBV receptor. In particular, we will determine whether HBIG could neutralize the infectivity of vaccine escape mutants. A unique feature of HBV is that majority of the S protein is secreted as the noninfectious subviral particles that exceed virions by a stunning 1,000 fold or greater. Considering that the S domain interacts with heparan sulfate proteoglycan (HSPG), the low-affinity HBV receptor, Aim 3 will examine whether subviral particles interfere with HBV infectivity by competitive binding to HSPG. We will also explore whether they promote HBV infectivity in the presence of anti-S antibodies by serving as decoys. This could explain why breakthrough infection could also be caused by the wild-type virus when the viral load is high. In summary, the proposed studies will evaluate the biological fitness of vaccine escape mutants alone or together with a compensatory mutation, and verify two alternative mechanisms of breakthrough infection. If anti-S antibodies cannot neutralize the infectivity of vaccine escape mutants, then future HBV vaccine should include preS sequence found in the large and middle envelope proteins as well.

Public Health Relevance

This application will examine how impaired virus particle secretion by hepatitis B virus vaccine escape mutants can be rescued, and whether antibodies raised against the wild-type virus can block the infectivity of such mutants. The findings will hel determine whether the current strategy to prevent maternal-infantile transmission of hepatitis B virus infection is flawed.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI116639-03
Application #
9206875
Study Section
Virology - B Study Section (VIRB)
Program Officer
Koshy, Rajen
Project Start
2015-02-01
Project End
2020-01-31
Budget Start
2017-02-01
Budget End
2018-01-31
Support Year
3
Fiscal Year
2017
Total Cost
$362,250
Indirect Cost
$137,250
Name
Rhode Island Hospital
Department
Type
Independent Hospitals
DUNS #
075710996
City
Providence
State
RI
Country
United States
Zip Code
02903
Lee, Jiwon; Zong, Li; Krotow, Alexander et al. (2018) N-Linked Glycosylation Is Not Essential for Sodium Taurocholate Cotransporting Polypeptide To Mediate Hepatitis B Virus Infection In Vitro. J Virol 92:
Bi, Xiaohui; Tong, Shuping (2018) Impact of immune escape mutations and N-linked glycosylation on the secretion of hepatitis B virus virions and subviral particles: Role of the small envelope protein. Virology 518:358-368
Zong, Li; Qin, Yanli; Jia, Haodi et al. (2017) Differential regulation of hepatitis B virus core protein expression and genome replication by a small upstream open reading frame and naturally occurring mutations in the precore region. Virology 505:155-161
Qin, Yanli; Wang, Yong-Xiang; Zhang, Jiming et al. (2017) Generation of Replication-Competent Hepatitis B Virus Genome from Blood Samples for Functional Characterization. Methods Mol Biol 1540:219-226
Zhou, Huailiang; Gewaily, Dina; Ahn, Sang Hoon et al. (2017) Sequence analysis and functional characterization of full-length hepatitis B virus genomes from Korean cirrhotic patients with or without liver cancer. Virus Res 235:86-95
Zhang, Fei; Tang, Xiaoli; Garcia, Tamako et al. (2017) Characterization of contrasting features between hepatitis B virus genotype A and genotype D in small envelope protein expression and surface antigen secretion. Virology 503:52-61
Qin, Yanli; Zhou, Xueshi; Jia, Haodi et al. (2016) Stronger enhancer II/core promoter activities of hepatitis B virus isolates of B2 subgenotype than those of C2 subgenotype. Sci Rep 6:30374
Tong, Shuping; Revill, Peter (2016) Overview of hepatitis B viral replication and genetic variability. J Hepatol 64:S4-S16
Zong, Li; Qin, Yanli; Jia, Haodi et al. (2016) Two-way molecular ligation for efficient conversion of monomeric hepatitis B virus DNA constructs into tandem dimers. J Virol Methods 233:46-50
Chen, Chaoyang; Jia, Haodi; Zhang, Fei et al. (2016) Functional characterization of hepatitis B virus core promoter mutants revealed transcriptional interference among co-terminal viral mRNAs. J Gen Virol 97:2668-2676

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