Soerensen Andreas, Popovic Filip, Olesen Christina Holmboe, Mendez Blanca Lopez, Lohse Brian, Chen Zhaochun, Farci Patrizia, Purcell Robert H, Alter Harvey J, Barfod Lea Klingenberg, Bukh Jens, Prentoe Jannick
Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Hvidovre and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, Copenhagen University Hospital, University of Copenhagen, Copenhagen, Denmark.
Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
PLoS Pathog. 2025 Mar 28;21(3):e1012428. doi: 10.1371/journal.ppat.1012428. eCollection 2025 Mar.
Identification and characterization of antibody epitope targets on the hepatitis C virus (HCV) envelope proteins remain crucial for developing an effective vaccine. Building on prior research defining E1/E2 antibody epitope clustering, we screened a phage display library derived from a chronic HCV patient against detergent-extracted full-length E1/E2 from both the patient's acute-phase isolate (H77, genotype 1a) and a heterologous isolate (S52, genotype 3a). This approach yielded a panel of VH1-69 derived antibody fragments (Fabs) with similar characteristics. Interestingly, all members of the panel exhibited blocking activity against both antigenic region 2 and 3 (AR2 and AR3) in competition ELISAs, which contrasts with the behavior of most previously identified AR3-targeting antibodies. The VH1-69 derived binders had a high affinity for soluble E2 in both Fab and IgG formats, with dissociation constants in the low picomolar range. These Fab binders were broadly neutralizing against a panel of HCV cell culture viruses of genotype 1-6 with higher potency than the well-characterized reference Fab, AR3A. However, in the IgG format the antibodies had similar potency. These findings expand our understanding of potential targets for vaccine development by characterizing a panel of antibodies targeting an AR3 epitope also involving or occluding the back layer of E2. The broad neutralization and high affinity of these antibodies suggest a benefit to targeting both the back layer and the front layer of E2 in HCV vaccine designs to expand the repertoire of broadly neutralizing antibodies, thereby offering promise for the development of more effective preventive measures against this pervasive human pathogen.
确定丙型肝炎病毒（HCV）包膜蛋白上的抗体表位靶点并对其进行表征，对于开发有效的疫苗仍然至关重要。基于先前定义E1/E2抗体表位聚类的研究，我们用来自一名慢性HCV患者的噬菌体展示文库，针对从该患者急性期分离株（H77，1a基因型）和一个异源分离株（S52，3a基因型）中用去污剂提取的全长E1/E2进行筛选。这种方法产生了一组具有相似特征的源自VH1-69的抗体片段（Fabs）。有趣的是，该组中的所有成员在竞争ELISA中均表现出针对抗原区域2和3（AR2和AR3）的阻断活性，这与大多数先前鉴定的靶向AR3的抗体的行为形成对比。源自VH1-69的结合物以Fab和IgG形式对可溶性E2具有高亲和力，解离常数在低皮摩尔范围内。这些Fab结合物对1-6基因型的一组HCV细胞培养病毒具有广泛的中和作用，效力高于特征明确的参考Fab，即AR3A。然而，以IgG形式存在时，这些抗体具有相似的效力。这些发现通过表征一组靶向AR3表位（该表位也涉及或覆盖E2的后层）的抗体，扩展了我们对疫苗开发潜在靶点的理解。这些抗体的广泛中和作用和高亲和力表明，在HCV疫苗设计中靶向E2的后层和前层以扩大广泛中和抗体的库是有益的，从而为开发针对这种普遍存在的人类病原体的更有效预防措施带来希望。
