Structural polymorphism of the antigenic loop in HBV surface antigen dictates binding of diverse neutralizing antibodies

Abstract The Hepatitis B Virus (HBV) poses a significant health threat, causing millions of deaths each year. Hepatitis B surface antigen (HBsAg), the sole membrane protein on the HBV viral envelope, plays crucial roles in viral attachment to host cells and serves as the target for neutralizing anti...

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Main Authors: Xiao He, Weiyu Tao, Yunlu Kang, Jiaxuan Xu, Xiaoyu Liu, Lei Chen
Format: Article
Language:English
Published: Nature Publishing Group 2025-06-01
Series:Cell Discovery
Online Access:https://doi.org/10.1038/s41421-025-00803-2
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author Xiao He
Weiyu Tao
Yunlu Kang
Jiaxuan Xu
Xiaoyu Liu
Lei Chen
author_facet Xiao He
Weiyu Tao
Yunlu Kang
Jiaxuan Xu
Xiaoyu Liu
Lei Chen
author_sort Xiao He
collection DOAJ
description Abstract The Hepatitis B Virus (HBV) poses a significant health threat, causing millions of deaths each year. Hepatitis B surface antigen (HBsAg), the sole membrane protein on the HBV viral envelope, plays crucial roles in viral attachment to host cells and serves as the target for neutralizing antibodies (NAbs). Despite its functional and therapeutic significance, the mechanisms by which NAbs recognize HBsAg remain elusive. Here, we found that HBsAg proteins exist in distinct subtypes and are recognized by different groups of antibodies. Cryo-electron microscopy (Cryo-EM) structures of HBsAg dimers in complex with NAb Fab fragments reveal that the antigenic loop (AGL) of these distinct HBsAg types share a common structural core comprised of four β-strands. However, their surface structures exhibit unexpected polymorphism due to distinct disulfide bond linkages within the AGL region. This structural polymorphism determines the recognition of HBsAg by different groups of NAbs.
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issn 2056-5968
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publishDate 2025-06-01
publisher Nature Publishing Group
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series Cell Discovery
spelling doaj-art-7450a6739abf41debf5da27642ae13a82025-08-20T02:10:34ZengNature Publishing GroupCell Discovery2056-59682025-06-011111910.1038/s41421-025-00803-2Structural polymorphism of the antigenic loop in HBV surface antigen dictates binding of diverse neutralizing antibodiesXiao He0Weiyu Tao1Yunlu Kang2Jiaxuan Xu3Xiaoyu Liu4Lei Chen5State Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking UniversityState Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking UniversityState Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking UniversityState Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking UniversityAcademy for Advanced Interdisciplinary Studies, Peking UniversityState Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking UniversityAbstract The Hepatitis B Virus (HBV) poses a significant health threat, causing millions of deaths each year. Hepatitis B surface antigen (HBsAg), the sole membrane protein on the HBV viral envelope, plays crucial roles in viral attachment to host cells and serves as the target for neutralizing antibodies (NAbs). Despite its functional and therapeutic significance, the mechanisms by which NAbs recognize HBsAg remain elusive. Here, we found that HBsAg proteins exist in distinct subtypes and are recognized by different groups of antibodies. Cryo-electron microscopy (Cryo-EM) structures of HBsAg dimers in complex with NAb Fab fragments reveal that the antigenic loop (AGL) of these distinct HBsAg types share a common structural core comprised of four β-strands. However, their surface structures exhibit unexpected polymorphism due to distinct disulfide bond linkages within the AGL region. This structural polymorphism determines the recognition of HBsAg by different groups of NAbs.https://doi.org/10.1038/s41421-025-00803-2
spellingShingle Xiao He
Weiyu Tao
Yunlu Kang
Jiaxuan Xu
Xiaoyu Liu
Lei Chen
Structural polymorphism of the antigenic loop in HBV surface antigen dictates binding of diverse neutralizing antibodies
Cell Discovery
title Structural polymorphism of the antigenic loop in HBV surface antigen dictates binding of diverse neutralizing antibodies
title_full Structural polymorphism of the antigenic loop in HBV surface antigen dictates binding of diverse neutralizing antibodies
title_fullStr Structural polymorphism of the antigenic loop in HBV surface antigen dictates binding of diverse neutralizing antibodies
title_full_unstemmed Structural polymorphism of the antigenic loop in HBV surface antigen dictates binding of diverse neutralizing antibodies
title_short Structural polymorphism of the antigenic loop in HBV surface antigen dictates binding of diverse neutralizing antibodies
title_sort structural polymorphism of the antigenic loop in hbv surface antigen dictates binding of diverse neutralizing antibodies
url https://doi.org/10.1038/s41421-025-00803-2
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