Synthetic Biology and Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea.
Infectious Diseases Therapeutic Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon, 34114, Republic of Korea; Graduate School of New Drug Discovery and Development, Chungnam National University, Daejeon, 34134, Republic of Korea.
Antiviral Res. 2023 May;213:105591. doi: 10.1016/j.antiviral.2023.105591. Epub 2023 Mar 31.
Influenza A virus continuously infects humans and the antigenic shifts of this respiratory virus enable it to cross the species barrier, threatening public health with the risk of pandemics. Broadly neutralizing antibodies (bnAbs) that target the antigenic surface glycoprotein, hemagglutinin (HA), of influenza A virus protect against various subtypes of the virus. Here, we screened a human scFv library, through phage display and panning against recombinant HA proteins, to discover human monoclonal antibodies (mAbs) that are broadly active. Consequently, two human mAbs, named G1 and G2, were identified, which target the HA proteins of the H1N1 and H3N2 subtypes, respectively. G1 was shown to have broad binding ability to different HA subtypes of group 1. By contrast, G2 had higher binding affinity but sensed exclusively H3 subtype-derived HAs. In a cell culture-based virus-neutralizing assay, both G1 and G2 efficiently suppressed infection of the parental influenza A viruses of H1N1 and H3N2 subtypes. Mode-of-action studies showed that the G1 antibody blocked HA2-mediated membrane fusion. Meanwhile, G2 inhibited HA1-mediated viral attachment to host cells. It is noteworthy that both antibodies elicited antibody-dependent cellular cytotoxicity (ADCC) activities by recruiting FcγRIIIA-expressing effector cells. In mouse challenge models, single-shot, intraperitoneal administration of chimeric G1 and G2 antibodies with the mouse IgG constant region completely protected mice from viral infections at doses above 10 and 1 mg/kg, respectively. The newly identified bnAbs, G1 and G2, could provide insight into the development of broad-spectrum antivirals against future pandemic influenza A virus involving group 1- or H3-subtyped strains.
甲型流感病毒持续感染人类，这种呼吸道病毒的抗原转变使其能够跨越物种屏障，对大流行的公共卫生构成威胁。针对甲型流感病毒抗原表面糖蛋白血凝素 (HA) 的广谱中和抗体 (bnAb) 可预防各种亚型的病毒感染。在此，我们通过噬菌体展示和对重组 HA 蛋白的淘选，从人源 scFv 文库中筛选出广谱活性的人源单克隆抗体 (mAb)。结果，鉴定出两种分别针对 H1N1 和 H3N2 亚型 HA 蛋白的人源 mAb，命名为 G1 和 G2。G1 与 1 组不同 HA 亚型均具有广泛的结合能力，而 G2 则对仅来源于 H3 亚型的 HA 具有更高的亲和力。在基于细胞培养的病毒中和试验中，G1 和 G2 均能有效抑制亲本 H1N1 和 H3N2 亚型流感 A 病毒的感染。作用模式研究表明，G1 抗体阻断了 HA2 介导的膜融合。同时，G2 抑制了 HA1 介导的病毒与宿主细胞的结合。值得注意的是，两种抗体通过募集表达 FcγRIIIA 的效应细胞，均能引发抗体依赖的细胞毒性 (ADCC) 活性。在小鼠攻毒模型中，嵌合 G1 和 G2 抗体与小鼠 IgG 恒定区的单次腹腔注射，在剂量高于 10 和 1 mg/kg 时，完全保护了小鼠免受病毒感染。新鉴定的广谱中和抗体 G1 和 G2，为开发针对未来涉及 1 组或 H3 型株的大流行流感 A 病毒的广谱抗病毒药物提供了思路。
