Chan Che-Man, Chu Hin, Wang Yixin, Wong Bosco Ho-Yin, Zhao Xiaoyu, Zhou Jie, Yang Dong, Leung Sze Pui, Chan Jasper Fuk-Woo, Yeung Man-Lung, Yan Jinghua, Lu Guangwen, Gao George Fu, Yuen Kwok-Yung
State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Hong Kong Special Administrative Region, China Department of Microbiology, University of Hong Kong, Hong Kong Special Administrative Region, China.
Department of Microbiology, University of Hong Kong, Hong Kong Special Administrative Region, China.
J Virol. 2016 Sep 29;90(20):9114-27. doi: 10.1128/JVI.01133-16. Print 2016 Oct 15.
The spike proteins of coronaviruses are capable of binding to a wide range of cellular targets, which contributes to the broad species tropism of coronaviruses. Previous reports have demonstrated that Middle East respiratory syndrome coronavirus (MERS-CoV) predominantly utilizes dipeptidyl peptidase 4 (DPP4) for cell entry. However, additional cellular binding targets of the MERS-CoV spike protein that may augment MERS-CoV infection have not been further explored. In the current study, using the virus overlay protein binding assay (VOPBA), we identified carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) as a novel cell surface binding target of MERS-CoV. CEACAM5 coimmunoprecipitated with the spike protein of MERS-CoV in both overexpressed and endogenous settings. Disrupting the interaction between CEACAM5 and MERS-CoV spike with anti-CEACAM5 antibody, recombinant CEACAM5 protein, or small interfering RNA (siRNA) knockdown of CEACAM5 significantly inhibited the entry of MERS-CoV. Recombinant expression of CEACAM5 did not render nonpermissive baby hamster kidney (BHK21) cells susceptible to MERS-CoV infection. Instead, CEACAM5 overexpression significantly enhanced the attachment of MERS-CoV to the BHK21 cells. More importantly, the entry of MERS-CoV was increased when CEACAM5 was overexpressed in permissive cells, which suggested that CEACAM5 could facilitate MERS-CoV entry in conjunction with DPP4 despite not being able to support MERS-CoV entry independently. Taken together, the results of our study identified CEACAM5 as a novel cell surface binding target of MERS-CoV that facilitates MERS-CoV infection by augmenting the attachment of the virus to the host cell surface.
Infection with the Middle East respiratory syndrome coronavirus (MERS-CoV) is associated with the highest mortality rate among all known human-pathogenic coronaviruses. Currently, there are no approved vaccines or therapeutics against MERS-CoV infection. The identification of carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) as a novel cell surface binding target of MERS-CoV advanced our knowledge on the cell binding biology of MERS-CoV. Importantly, CEACAM5 could potentiate the entry of MERS-CoV by functioning as an attachment factor. In this regard, CEACAM5 could serve as a novel target, in addition to dipeptidyl peptidase-4 (DPP4), in the development of antiviral strategies for MERS-CoV.
冠状病毒的刺突蛋白能够结合多种细胞靶点，这有助于冠状病毒具有广泛的宿主嗜性。先前的报道表明，中东呼吸综合征冠状病毒（MERS-CoV）主要利用二肽基肽酶4（DPP4）进入细胞。然而，MERS-CoV刺突蛋白可能增强MERS-CoV感染的其他细胞结合靶点尚未得到进一步探索。在本研究中，我们使用病毒覆盖蛋白结合试验（VOPBA），鉴定癌胚抗原相关细胞粘附分子5（CEACAM5）为MERS-CoV新的细胞表面结合靶点。在过表达和内源性情况下，CEACAM5均与MERS-CoV的刺突蛋白共免疫沉淀。用抗CEACAM5抗体、重组CEACAM5蛋白或通过小干扰RNA（siRNA）敲低CEACAM5破坏CEACAM5与MERS-CoV刺突之间的相互作用，可显著抑制MERS-CoV的进入。CEACAM5的重组表达并未使非允许性的幼仓鼠肾（BHK21）细胞对MERS-CoV感染敏感。相反，CEACAM5的过表达显著增强了MERS-CoV与BHK21细胞的附着。更重要的是，当CEACAM5在允许性细胞中过表达时，MERS-CoV的进入增加，这表明CEACAM5虽不能独立支持MERS-CoV进入，但可与DPP4协同促进MERS-CoV进入。综上所述，我们的研究结果鉴定出CEACAM5是MERS-CoV新的细胞表面结合靶点，它通过增强病毒与宿主细胞表面的附着促进MERS-CoV感染。
中东呼吸综合征冠状病毒（MERS-CoV）感染在所有已知的人类致病性冠状病毒中死亡率最高。目前，尚无批准用于预防MERS-CoV感染的疫苗或治疗方法。癌胚抗原相关细胞粘附分子5（CEACAM5）作为MERS-CoV新的细胞表面结合靶点的鉴定，增进了我们对MERS-CoV细胞结合生物学的认识。重要的是，CEACAM5可作为一种附着因子增强MERS-CoV的进入。在这方面，除二肽基肽酶-4（DPP4）外，CEACAM5可作为MERS-CoV抗病毒策略开发中的新靶点。
