Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA.
Department of Cardiovascular Surgery, Changhai Institute of Cardiovascular Surgery, Shanghai 200433, China.
Viruses. 2018 Oct 16;10(10):563. doi: 10.3390/v10100563.
Members of the family Filoviridae, including Ebola virus (EBOV) and Marburg virus (MARV), cause severe hemorrhagic fever in humans and nonhuman primates. Given their high lethality, a comprehensive understanding of filoviral pathogenesis is urgently needed. In the present studies, we revealed that the exchange protein directly activated by () gene deletion protects vasculature in ex vivo explants from EBOV infection. Importantly, pharmacological inhibition of EPAC1 using EPAC-specific inhibitors (ESIs) mimicked the knockout phenotype in the ex vivo model. ESI treatment dramatically decreased EBOV infectivity in both ex vivo vasculature and in vitro vascular endothelial cells (ECs). Furthermore, postexposure protection of ECs against EBOV infection was conferred using ESIs. Protective efficacy of ESIs in ECs was observed also in MARV infection. Additional studies using a vesicular stomatitis virus pseudotype that expresses EBOV glycoprotein (EGP-VSV) confirmed that ESIs reduced infection in ECs. Ultrastructural studies suggested that ESIs blocked EGP-VSV internalization via inhibition of macropinocytosis. The inactivation of EPAC1 affects the early stage of viral entry after viral binding to the cell surface, but before early endosome formation, in a phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)-dependent manner. Our study delineated a new critical role of EPAC1 during EBOV uptake into ECs.
丝状病毒科的成员，包括埃博拉病毒（EBOV）和马尔堡病毒（MARV），会导致人类和非人类灵长类动物出现严重的出血热。鉴于它们的高致死率，迫切需要全面了解丝状病毒的发病机制。在本研究中，我们揭示了直接被激活的交换蛋白（）基因缺失可保护血管免受 EBOV 感染。重要的是，使用 EPAC 特异性抑制剂（ESIs）抑制 EPAC1 的药理作用，可在离体模型中模拟出的敲除表型。ESI 处理可显著降低离体血管和体外血管内皮细胞（ECs）中的 EBOV 感染性。此外，ESIs 可在暴露后保护 ECs 免受 EBOV 感染。ESIs 在 MARV 感染中也观察到对 ECs 的保护作用。使用表达 EBOV 糖蛋白（EGP-VSV）的水疱性口炎病毒假型进一步证实，ESIs 可降低 ECs 中的感染。超微结构研究表明，ESIs 通过抑制巨胞饮作用阻断 EGP-VSV 的内化。EPAC1 的失活以依赖于磷脂酰肌醇-4,5-二磷酸 3-激酶（PI3K）的方式，影响病毒结合到细胞表面后的早期阶段，即在早期内体形成之前，影响病毒的进入。我们的研究描绘了 EPAC1 在 EBOV 进入 ECs 过程中的新的关键作用。
