Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA; Biosecurity Research Institute, Kansas State University, Manhattan, KS, USA; National Bio- and Agro-Defense Facility Scientist Training Program, Animal and Plant Health Inspection Service, United States Department of Agriculture, USA.
Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA; Biosecurity Research Institute, Kansas State University, Manhattan, KS, USA.
Antiviral Res. 2020 Feb;174:104675. doi: 10.1016/j.antiviral.2019.104675. Epub 2019 Dec 9.
Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus endemic in the Asia Pacific region. Despite use of several highly effective vaccines, it is estimated that up to 44,000 new cases of Japanese encephalitis (JE) occur every year including 14,000 deaths and 24,000 survivors with permanent sequelae. Humoral immunity induced by vaccination is critical for effective protection. Potently neutralizing antibodies reactive with the JEV envelope (E) protein are important since protective immune responses induced by both live-attenuated and inactivated JE vaccines target the E protein. Our understanding of how vaccine-induced humoral immunity protects vaccinees from morbidity and mortality is, however, limited and largely obtained from in vitro studies. With the exception of neurovirulence mouse models, very few platforms are available for evaluating the protective efficacy of neutralizing antibodies against JEV in vivo. Swine are a major amplifying host in the natural JEV transmission cycle and develop multiple pathological outcomes similar to humans infected with JEV. In this study, prophylactic passive immunization was performed in a miniature swine model, using two vaccination-induced monoclonal antibodies (mAb), JEV-31 and JEV-169. These were selected as representatives for antibodies reactive with the major antigenic structures in the E protein of JEV and related flaviviruses. JEV-31 recognizes the lateral ridge of E protein domain III (EDIII) whilst JEV-169 has a broad footprint of binding involving residues throughout domains I (EDI) and II (EDII) of the E protein. Detection of neutralizing antibodies in the serum of immunized animals mimics the presence of neutralizing antibodies in vaccinated individuals. Passive immunization with both mAbs significantly reduced the severity of diseases that resemble the symptoms of human JE including fever, viremia, viral shedding, systemic infection, and neuroinvasion. In contrast to the uniformed decrease of viral loads in lymphoid and central nervous systems, distinct kinetics in the onset of fever and viremia between animals receiving JEV-31 and JEV-169 suggest potential differences in immune protection mechanisms between anti-EDI and anti-EDIII neutralizing antibodies elicited by vaccination. Our data demonstrate the feasibility of using swine models in characterizing the protective humoral immunity against JEV and increase our understanding of how clonal populations of anti-E mAbs derived from JE vaccination protect against infection in vivo.
日本脑炎病毒 (JEV) 是一种蚊媒黄病毒，流行于亚太地区。尽管使用了几种高效疫苗，但据估计，每年仍有多达 44000 例新的日本脑炎 (JE) 病例，包括 14000 例死亡和 24000 例幸存者留有永久性后遗症。疫苗诱导的体液免疫对于有效保护至关重要。与 JEV 包膜 (E) 蛋白反应的强效中和抗体很重要，因为活减毒和灭活 JE 疫苗诱导的保护性免疫反应针对的是 E 蛋白。然而，我们对疫苗诱导的体液免疫如何保护疫苗接种者免受发病率和死亡率的影响的理解是有限的，并且主要是从体外研究中获得的。除了神经毒力小鼠模型外，很少有平台可用于评估体内中和抗体对 JEV 的保护效力。猪是天然 JEV 传播循环中的主要扩增宿主，并表现出与感染 JEV 的人类相似的多种病理结局。在这项研究中，使用两种疫苗诱导的单克隆抗体 (mAb)，JEV-31 和 JEV-169，对小型猪模型进行了预防性被动免疫。这些 mAb 被选为代表与 JEV 和相关黄病毒 E 蛋白主要抗原结构反应的抗体。JEV-31 识别 E 蛋白结构域 III (EDIII) 的侧脊，而 JEV-169 具有广泛的结合足迹，涉及 E 蛋白的结构域 I (EDI) 和 II (EDII) 中的多个残基。在免疫动物的血清中检测到中和抗体模拟了接种个体中存在的中和抗体。用两种 mAb 进行被动免疫可显著降低疾病的严重程度，这些疾病类似于人类 JE 的症状，包括发热、病毒血症、病毒脱落、全身感染和神经侵袭。与淋巴样和中枢神经系统中病毒载量的均匀下降相反，接受 JEV-31 和 JEV-169 治疗的动物之间发热和病毒血症发作的不同动力学表明，疫苗接种诱导的抗 EDI 和抗 EDIII 中和抗体之间的免疫保护机制可能存在差异。我们的数据证明了使用猪模型来描述针对 JEV 的保护性体液免疫的可行性，并增加了我们对 JE 疫苗接种产生的抗-E 单克隆抗体克隆群体如何在体内抵抗感染的理解。
