School of Molecular Medical Sciences, The University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom.
Hepatology. 2013 Sep;58(3):932-9. doi: 10.1002/hep.26430. Epub 2013 Jul 30.
Severe liver disease caused by chronic hepatitis C virus is the major indication for liver transplantation. Despite recent advances in antiviral therapy, drug toxicity and unwanted side effects render effective treatment in liver-transplanted patients a challenging task. Virus-specific therapeutic antibodies are generally safe and well-tolerated, but their potential in preventing and treating hepatitis C virus (HCV) infection has not yet been realized due to a variety of issues, not least high production costs and virus variability. Heavy-chain antibodies or nanobodies, produced by camelids, represent an exciting antiviral approach; they can target novel highly conserved epitopes that are inaccessible to normal antibodies, and they are also easy to manipulate and produce. We isolated four distinct nanobodies from a phage-display library generated from an alpaca immunized with HCV E2 glycoprotein. One of them, nanobody D03, recognized a novel epitope overlapping with the epitopes of several broadly neutralizing human monoclonal antibodies. Its crystal structure revealed a long complementarity determining region (CD3) folding over part of the framework that, in conventional antibodies, forms the interface between heavy and light chain. D03 neutralized a panel of retroviral particles pseudotyped with HCV glycoproteins from six genotypes and authentic cell culture-derived particles by interfering with the E2-CD81 interaction. In contrast to some of the most broadly neutralizing human anti-E2 monoclonal antibodies, D03 efficiently inhibited HCV cell-to-cell transmission.
This is the first description of a potent and broadly neutralizing HCV-specific nanobody representing a significant advance that will lead to future development of novel entry inhibitors for the treatment and prevention of HCV infection and help our understanding of HCV cell-to-cell transmission.
慢性丙型肝炎病毒引起的严重肝脏疾病是肝移植的主要指征。尽管抗病毒治疗最近取得了进展，但药物毒性和不良反应使得肝移植患者的有效治疗成为一项具有挑战性的任务。病毒特异性治疗性抗体通常是安全且耐受良好的，但由于各种问题，包括高生产成本和病毒变异性，它们在预防和治疗丙型肝炎病毒（HCV）感染方面的潜力尚未得到实现。重链抗体或纳米抗体是由骆驼科动物产生的，代表了一种令人兴奋的抗病毒方法；它们可以靶向新型高度保守的表位，这些表位是普通抗体无法接触到的，而且它们也易于操作和生产。我们从用 HCV E2 糖蛋白免疫的羊驼产生的噬菌体展示文库中分离出四种不同的纳米抗体。其中一种纳米抗体 D03 识别一个新的表位，该表位与几种广泛中和的人单克隆抗体的表位重叠。其晶体结构揭示了一个长的互补决定区（CD3）折叠部分框架，在常规抗体中，该框架形成重链和轻链之间的界面。D03 通过干扰 E2-CD81 相互作用来中和六种基因型的 HCV 糖蛋白假型的逆转录病毒颗粒和真实细胞培养衍生的颗粒。与一些最广泛中和的人抗 E2 单克隆抗体相比，D03 有效地抑制了 HCV 的细胞间传播。
这是首次描述一种有效的、广泛中和的 HCV 特异性纳米抗体，这是一项重大进展，将导致新型进入抑制剂的开发，用于治疗和预防 HCV 感染，并帮助我们理解 HCV 的细胞间传播。
