Human cytomegalovirus (HCMV) is a ubiquitous pathogen that can cause developmental disorders following congenital infection and life-threatening complications among transplant patients. Potent neutralizing monoclonal antibodies (MAbs) are promising drug candidates against HCMV infection. HCMV can infect a broad range of cell types. Therefore, single neutralizing antibodies targeting one HCMV glycoprotein often lack either potency or broad cell-type coverage. We previously characterized two human-derived HCMV neutralizing MAbs. One was the broadly neutralizing MAb 3-25, which targets the antigenic domain 2 of glycoprotein B (gB). The other was the highly potent MAb 2-18, which specifically recognizes the gH/gL/pUL128/130/131 complex (pentamer). To combine the strengths of gB- and pentamer-targeting MAbs, we developed an IgG–single-chain variable fragment (scFv) bispecific antibody by fusing the 2-18 scFv to the heavy-chain C terminus of MAb 3-25. The resulting bispecific antibody showed high-affinity binding to both gB and pentamer. Functionally, the bispecific antibody demonstrated a combined neutralization breadth and potency of the parental MAbs in multiple cell lines and inhibited postinfection viral spreading. Furthermore, the bispecific antibody was easily produced in CHO cells at a yield above 1 g/liter and showed a single-dose pharmacokinetic profile comparable to that of parental MAb 3-25 in rhesus macaques. Importantly, the bispecific antibody retained broadly and potent neutralizing activity after 21 days in circulation. Taken together, our research provides a proof-of-concept study for developing bispecific neutralizing antibody therapies against HCMV infection.

中文翻译：

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靶向糖蛋白B和人巨细胞病毒gH / gL / pUL128 / 130/131复合物的强效双特异性中和抗体

人类巨细胞病毒（HCMV）是一种普遍存在的病原体，可引起先天性感染和移植患者危及生命的并发症后发生发育障碍。有力的中和性单克隆抗体（MAb）是抗HCMV感染的有前途的候选药物。HCMV可以感染多种细胞类型。因此，靶向一种HCMV糖蛋白的单一中和抗体常常缺乏效力或广泛的细胞类型覆盖。我们先前表征了两个人源性HCMV中和单克隆抗体。一种是广泛中和的MAb 3-25，其靶向糖蛋白B（gB）的抗原结构域2。另一个是高效能的MAb 2-18，可特异性识别gH / gL / pUL128 / 130/131复合物（五聚物）。为了结合针对gB和五聚体的单克隆抗体的优势，我们通过将2-18 scFv与MAb 3-25的重链C末端融合，开发了IgG单链可变片段（scFv）双特异性抗体。所得双特异性抗体显示出与gB和pentamer的高亲和力结合。在功能上，双特异性抗体在多种细胞系中显示了母体单抗的结合中和广度和效力，并抑制了感染后病毒的扩散。此外，双特异性抗体很容易在CHO细胞中以高于1 g / l的产量产生，并显示出与猕猴中亲代MAb 3-25相当的单剂量药代动力学特征。重要的是，在循环21天后，双特异性抗体广泛保留了有效的中和活性。在一起