Chuang Yung-Chun, Lin Jessica, Lin Yee-Shin, Wang Shuying, Yeh Trai-Ming
Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan 701; Center of Infectious Disease and Signaling Research, College of Medicine, National Cheng Kung University, Tainan, Taiwan 701; and.
Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan 701;
J Immunol. 2016 Feb 1;196(3):1218-26. doi: 10.4049/jimmunol.1500057. Epub 2015 Dec 28.
Dengue virus (DENV) infection is the most common mosquito-borne viral disease, and it can cause life-threatening dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Abnormal activation of the coagulation and fibrinolysis system is one of the hallmarks of DHF/DSS. However, the mechanism underlying hemorrhage in DHF/DSS remains elusive. In previous studies, plasminogen (Plg) cross-reactive Abs, which can recognize DENV nonstructural protein (NS) 1, have been found in dengue patients. However, it is unclear whether these Abs are indeed induced by DENV NS1. Thus, we immunized mice with recombinant NS1 from both bacteria and drosophila to determine whether NS1 can induce Plg cross-reactive Abs. The results from the NS1-immunized mouse sera indicated that NS1 immunization induced Abs that could cross-react with Plg. To study the effects of these NS1-induced Plg cross-reactive Abs on fibrinolysis, we isolated several Plg cross-reactive anti-NS1 mAbs from these mice and found that some of them could enhance Plg activation. In addition, epitope mapping with a phage-displayed random peptide library revealed that one of these mAbs (2A5) could recognize NS1 C-terminal residues 305-311, which share sequence homology with Plg residues 590-597. A synthetic peptide of NS1 residues 305-311 could inhibit the binding of both 2A5 and its Fab to Plg and its enhanced activation. Thus, our results suggest that DENV NS1 can induce Plg cross-reactive Abs through molecular mimicry, which can enhance Plg activation and may contribute to the pathogenesis of DHF/DSS.
登革病毒（DENV）感染是最常见的蚊媒病毒病，可导致危及生命的登革出血热（DHF）和登革休克综合征（DSS）。凝血和纤溶系统的异常激活是DHF/DSS的特征之一。然而，DHF/DSS出血的潜在机制仍不清楚。在先前的研究中，已在登革热患者中发现可识别DENV非结构蛋白（NS）1的纤溶酶原（Plg）交叉反应性抗体。然而，尚不清楚这些抗体是否确实由DENV NS1诱导。因此，我们用来自细菌和果蝇的重组NS1免疫小鼠，以确定NS1是否能诱导Plg交叉反应性抗体。NS1免疫小鼠血清的结果表明，NS1免疫诱导了可与Plg交叉反应的抗体。为了研究这些NS1诱导的Plg交叉反应性抗体对纤溶的影响，我们从这些小鼠中分离出几种Plg交叉反应性抗NS1单克隆抗体，发现其中一些可以增强Plg激活。此外，用噬菌体展示随机肽库进行表位作图显示，其中一种单克隆抗体（2A5）可以识别NS1 C末端残基305-311，其与Plg残基590-597具有序列同源性。NS1残基305-311的合成肽可以抑制2A5及其Fab与Plg的结合及其增强的激活。因此，我们的结果表明，DENV NS1可通过分子模拟诱导Plg交叉反应性抗体，这可增强Plg激活并可能导致DHF/DSS的发病机制。
