An E. coli-produced single-chain variable fragment (scFv) targeting hepatitis B virus surface protein potently inhibited virion secretion.
Fiche publication
Date publication
décembre 2018
Journal
Antiviral research
Auteurs
Membres identifiés du Cancéropôle Est :
Pr BAUMERT Thomas
Tous les auteurs :
Li C, Wang Y, Liu T, Niklasch M, Qiao K, Durand S, Chen L, Liang M, Baumert TF, Tong S, Nassal M, Wen YM, Wang YX
Lien Pubmed
Résumé
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 (IC = 1.8 nM). Strikingly, low concentrations of G12-scFv blocked virion secretion from HBV producing cells (IC = 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.
Référence
Antiviral Res.. 2018 Dec 29;: