Antiviral Res. 2018 Dec 29. pii: S0166-3542(18)30207-9. doi: 10.1016/j.antiviral.2018.12.019. [Epub ahead of print]
An E. coli-produced single-chain variable fragment (scFv) targeting hepatitis B virus surface protein potently inhibited virion secretion.
Li C1, Wang Y1, Liu T1, Niklasch M2, Qiao K1, Durand S3, Chen L1, Liang M4, Baumert TF5, Tong S1, Nassal M2, Wen YM1, Wang YX6.
Author information
1
Key Laboratory of Medical Molecular Virology, Ministry of Education and Ministry of Health, Shanghai Medical College of Fudan University, Shanghai, China.
2
University Hospital Freiburg, Department of Internal Medicine II/Molecular Biology, Freiburg, Germany.
3
Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France.
4
Key Laboratory for Medical Virology, NHFPC, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, China.
5
Inserm, U1110, Institut de Recherche sur les Maladies Virales et Hépatiques, Strasbourg, France; Université de Strasbourg, Strasbourg, France; Institut Hospitalo-Universitaire, Pôle 5 Hépato-digestif, Nouvel Hôpital Civil, Strasbourg, France.
6
Key Laboratory of Medical Molecular Virology, Ministry of Education and Ministry of Health, Shanghai Medical College of Fudan University, Shanghai, China. Electronic address: [email protected].
Abstract
Hepatitis B virus (HBV) envelopes as well as empty subviral particles carry in their lipid membranes the small (S), middle (M), and large (L) surface proteins, collectively known as hepatitis B surface antigen (HBsAg). Due to their common S domain all three proteins share a surface-exposed hydrophilic antigenic loop (AGL) with a complex disulfide bridge-dependent structure. The AGL is critical for HBV infectivity and virion secretion, and thus represents a major target for neutralizing antibodies. Previously, a human monoclonal antibody (mAb) targeting a conformational epitope in the AGL, IgG12, exhibited 1000-fold higher neutralizing activity than hepatitis B immune globulin (HBIG). Here we designed a single-chain variable fragment (scFv) homolog of IgG12, G12-scFv, which could be efficiently produced in soluble form in the cytoplasm of E. coli SHuffle cells. Independent in vitro assays verified specific binding of G12-scFv to a conformational S epitope shared with IgG12. Despite 20-fold lower affinity, G12-scFv but not an irrelevant scFv potently neutralized HBV infection of susceptible hepatoma cells (IC50 = 1.8 nM). Strikingly, low concentrations of G12-scFv blocked virion secretion from HBV producing cells (IC50 = 1.25 nM) without disturbing intracellular viral replication, whereas extracellular HBsAg was reduced only at >100-fold higher though still nontoxic concentration. The inhibitory effects correlated with S binding specificity and presumably also G12-scFv internalization into cells. Together these data suggest G12-scFv as a highly specific yet easily accessible novel tool for basic, diagnostic, and possibly future therapeutic applications.
1
复旦大学上海医学院医学分子病毒学教育部重点实验室，上海，上海。
2
弗莱堡大学医院，内科II /分子生物学，德国弗赖堡。
3
Inserm，U1110，Institut de Recherche sur les Maladies ViralesetHépatiques，Strasbourg，France。
4
中国疾病预防控制中心国家病毒病预防控制所，NHFPC医学病毒学重点实验室，北京，中国。
五
Inserm，U1110，Institut de Recherche sur les Maladies ViralesetHépatiques，Strasbourg，France;法国斯特拉斯堡斯特拉斯堡大学; Institut Hospitalo-Universitaire，Pôle5Hépato-digestif，NouvelHôpitalCivil，法国斯特拉斯堡。
6
复旦大学上海医学院医学分子病毒学教育部重点实验室，上海，上海。电子地址：[email protected]。
