Identification of Signaling Pathways Involved in Ebola Virus Entry Into Host Cells

Abstract

Ebola virus (EBOV) is an enveloped virus of the family Filoviridae that causes outbreaks of hemorrhagic fever and for which there are no FDA-approved antiviral therapies. EBOV entry involves internalization and trafficking within host cells to facilitate delivery of the virus to its intracellular receptor, Niemann-Pick C1 (NPC1), which is localized in late endosomes/lysosomes. Given the requirements for internalization and endolysosomal trafficking, we hypothesized that EBOV activates signaling pathways to induce its uptake and regulate its trafficking to NPC1+ cellular compartments. To determine if signaling events induced by the virus play a role in infection, we screened a library of kinase inhibitors for their effect on infection by MLV pseudotypes bearing EBOV or vesicular stomatitis virus (VSV) glycoproteins. We subsequently identified and sought to characterize inhibitors of receptor tyrosine kinases (RTKs), sphingosine kinases (SKs), and diacylglycerol kinases (DGKs). Mechanistic studies revealed that EBOV activates RTK signaling to promote its trafficking to entry-conducive intracellular compartments. In addition, we also found that SKs are important for proper endocytic trafficking of EBOV to NPC1, while DGKs are required for EBOV internalization. Lastly, many of the kinase inhibitors we identified also inhibit entry of other late-penetrating viruses and may serve as potential starting points for the development of broad-spectrum host-directed antiviral therapeutics.