A Diacylglycerol Kinase Inhibitor, R-59-022, Blocks Filovirus Internalization in Host Cells.

Corina Stewart,Morgan Fullerton,Nicholas Leblond,Marceline Côté,Stephanie Dorion,Tyler Smith,Darwyn Kobasa,Marie Ottenbrite,Shirley Qiu

doi:10.3390/v11030206

Abstract

Filoviruses, such as Ebola virus (EBOV) and Marburg virus, are causative agents of unpredictable outbreaks of severe hemorrhagic fevers in humans and non-human primates. For infection, filoviral particles need to be internalized and delivered to intracellular vesicles containing cathepsin proteases and the viral receptor Niemann-Pick C1. Previous studies have shown that EBOV triggers macropinocytosis of the viral particles in a glycoprotein (GP)-dependent manner, but the molecular events required for filovirus internalization remain mostly unknown. Here we report that the diacylglycerol kinase inhibitor, R-59-022, blocks EBOV GP-mediated entry into Vero cells and bone marrow-derived macrophages. Investigation of the mode of action of the inhibitor revealed that it blocked an early step in entry, more specifically, the internalization of the viral particles via macropinocytosis. Finally, R-59-022 blocked viral entry mediated by a panel of pathogenic filovirus GPs and inhibited growth of replicative Ebola virus. Taken together, our studies suggest that R-59-022 could be used as a tool to investigate macropinocytic uptake of filoviruses and could be a starting point for the development of pan-filoviral therapeutics.

Highlights

Filoviruses, which include Ebola virus (EBOV) and Marburg virus (MARV), are zoonotic pathogens that can cause unpredictable outbreaks of severe hemorrhagic fevers in humans and non-human primates [1]
We found that entry of pseudotypes and viral-like particles bearing the EBOV GP, but not those harboring the vesicular stomatitis virus (VSV)-G protein was blocked by R-59-022 in Vero cells
Because previous studies have shown that the mucin region of GP is not required for uptake via macropinocytosis or for cathepsin/Niemann-Pick C1 (NPC1) dependence, we used a mucin-deleted version of EBOV GP, which allows higher viral particle yields [8,9,16]

Summary

Introduction

Filoviruses, which include Ebola virus (EBOV) and Marburg virus (MARV), are zoonotic pathogens that can cause unpredictable outbreaks of severe hemorrhagic fevers in humans and non-human primates [1]. The Filoviridae family contains three distinct genera: Ebolavirus that comprises five viruses (Bundibugyo (BDBV), EBOV, Reston (RESTV), Sudan (SUDV), and Taï. While most outbreaks occurred in Central and. West Africa, recent studies have uncovered the high diversity and large geographical distributions of filoviruses including the discovery of new bat-borne filoviruses in China [4]. Viruses 2019, 11, 206 trial [5,6], these do not protect from infection by all filoviruses. There is currently no FDA-approved antiviral against any of these highly pathogenic viruses

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Conclusion