Supplementary Material for: Activating Natural Killer Cell Receptors, Selectins, and Inhibitory Siglecs Recognize Ebolavirus Glycoprotein

Expression of the extensively glycosylated Ebolavirus glycoprotein (EBOV-GP) induces physical alterations of surface molecules and plays a crucial role in viral pathogenicity. Here we investigate the interactions of EBOV-GP with host surface molecules using purified EBOV-GP, EBOV-GP-transfected cell lines, and EBOV-GP-pseudotyped lentiviral particles. Subsequently, we wanted to examine which receptors are involved in this recognition by binding studies to cells transfected with the EBOV-GP as well as to recombinant soluble EBOV-GP. As the viral components can also bind to inhibitory receptors of immune cells (e.g., Siglecs, TIM-1), they can even suppress the activity of immune effector cells. Our data show that natural killer (NK) cell receptors NKp44 and NKp46, selectins (CD62E/P/L), the host factors DC-SIGNR/DC-SIGN, and inhibitory Siglecs function as receptors for EBOV-GP. Our results show also moderate to strong avidity of homing receptors (P-, L-, and E-selectin) and DC-SIGNR/DC-SIGN to purified EBOV-GP, to cells transfected with EBOV-GP, as well as to the envelope of a pseudotyped lentiviral vector carrying the EBOV-GP. The concomitant activation and inhibition of the immune system exemplifies the evolutionary antagonism between the immune system and pathogens. Altogether these interactions with activating and inhibitory receptors result in a reduced NK cell-mediated lysis of EBOV-GP-expressing cells. Modulation of these interactions may provide new strategies for treating infections caused by this virus.

广泛糖基化的埃博拉病毒糖蛋白（Ebolavirus glycoprotein, EBOV-GP）的表达会引发宿主表面分子的结构改变，且在病毒致病过程中发挥关键作用。本研究借助纯化的埃博拉病毒糖蛋白、转染埃博拉病毒糖蛋白的细胞系以及包被埃博拉病毒糖蛋白的假型慢病毒颗粒，探究埃博拉病毒糖蛋白与宿主表面分子的相互作用。随后，本研究通过结合实验——分别以转染埃博拉病毒糖蛋白的细胞与重组可溶性埃博拉病毒糖蛋白为底物——探究参与该识别过程的受体种类。由于病毒组分亦可结合免疫细胞的抑制性受体（如Siglecs、TIM-1），其甚至可抑制免疫效应细胞的活性。本研究数据显示，自然杀伤细胞（natural killer, NK）受体NKp44与NKp46、选择素（CD62E/P/L）、宿主因子DC-SIGNR/DC-SIGN以及抑制性Siglecs均可作为埃博拉病毒糖蛋白的受体。本研究结果同时显示，归巢受体（P-选择素、L-选择素与E-选择素）以及DC-SIGNR/DC-SIGN与纯化的埃博拉病毒糖蛋白、转染埃博拉病毒糖蛋白的细胞以及携带埃博拉病毒糖蛋白的假型慢病毒载体的包膜均具有中等至较强的结合亲和力。免疫系统的伴随性激活与抑制，正是免疫系统与病原体之间进化拮抗关系的典型体现。综上，这些与激活型及抑制型受体的相互作用会削弱自然杀伤细胞介导的、对表达埃博拉病毒糖蛋白的细胞的裂解作用。对这些相互作用进行调控，可为该病毒感染的治疗提供全新策略。