Key Points Neutralizing mAb 1G2 recognized only monomer E protein under nonreducing conditions. Broadly cross-reactive epitope 227GSSAGTWQN235 was identified. 1G2 could completely protect mice against lethal DTMUV challenge. The Flavivirus E protein induces protective immunity, and its Abs cause serious problems for serodiagnosis because of the difficulty in differentiating cross-reactive Abs. Moreover, cross-reactive Abs may increase disease severity after secondary Flavivirus infections via Ab-dependent enhancement. Cross-reactive epitopes are therefore critical for understanding serodiagnosis and improving the general knowledge of Flavivirus infections. A minimal epitope, 227GSSAGTWQN235, was identified by a neutralizing mAb 1G2 against duck Tembusu virus (DTMUV), which recognized only monomer E protein under nonreducing conditions. It was unexpectedly found that mutations in the epitope residues G231 or W233 completely abolished reactivity to 1G2 and sera from mice infected with Japanese encephalitis virus, West Nile virus, and Zika virus. An immunofluorescence assay confirmed that mAb 1G2 could cross-react with the E proteins from Japanese encephalitis virus, West Nile virus, and Zika virus. Protein and virus modeling revealed that the epitope was surface accessible in the mature virus and located in the hi loop of domain II. The neutralization of DTMUV by 1G2 played a clear therapeutic role in mouse models. The passive transfer of 1G2 resulted in 100% survival, reduced weight loss, and the complete clearance of DTMUV from the blood of BALB/c mice. Our findings document, for the first time to our knowledge, that mAb 1G2 targets the cross-reactive epitope on the hi loop of domain II in the E protein and might be of potential therapeutic value in treating DTMUV infection and improve the understanding of the issues related to serodiagnosis.

中文翻译：

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针对包膜蛋白域 II hi 环上的独特交叉反应表位的新型中和抗体保护小鼠免受鸭坦布苏病毒的侵害

关键点中和 mAb 1G2 在非还原条件下仅识别单体 E 蛋白。鉴定了广泛交叉反应的表位 227GSSAGTWQN235。1G2 可以完全保护小鼠免受致命的 DTMUV 攻击。黄病毒 E 蛋白诱导保护性免疫，由于难以区分交叉反应性抗体，其抗体会给血清学诊断带来严重问题。此外，交叉反应性抗体可能会通过抗体依赖性增强在继发黄病毒感染后增加疾病的严重程度。因此，交叉反应表位对于了解血清学诊断和提高黄病毒感染的一般知识至关重要。最小表位 227GSSAGTWQN235 由抗鸭坦布苏病毒 (DTMUV) 的中和 mAb 1G2 鉴定，该病毒在非还原条件下仅识别单体 E 蛋白。意外地发现，表位残基 G231 或 W233 的突变完全消除了对感染日本脑炎病毒、西尼罗河病毒和寨卡病毒的小鼠的 1G2 和血清的反应性。免疫荧光分析证实 mAb 1G2 可以与日本脑炎病毒、西尼罗河病毒和寨卡病毒的 E 蛋白发生交叉反应。蛋白质和病毒模型显示，该表位在成熟病毒中是表面可接近的，并且位于结构域 II 的高环中。1G2 对 DTMUV 的中和作用在小鼠模型中起到了明显的治疗作用。1G2 的被动转移导致 100% 存活，减少体重减轻，并从 BALB/c 小鼠的血液中完全清除 DTMUV。据我们所知，我们的发现首次记录了