Subcellular Characterization of the Molecular Determinants of Ebola Virus VP40 Trafficking and Assembly

Ebola virus is a single-stranded negative-sense RNA virus that can cause severe hemorrhagic fevers in humans. Ebola virus, along with other members of the filoviridae family, produce virions with a characteristic filamentous morphology. VP40 is the Ebola virus matrix protein, which is responsible for curving the host PM into filamentous buds. VP40 forms cytosolic homodimers via interactions in its N-terminal domain, while interactions in its C-terminal domain drive oligomerization into the 2D-crystalline matrix layer. While VP40 is expressed in the host cytosol and assembles on the inner leaflet of the plasma membrane (PM), trafficking between the cytosol and PM is not direct. Here, we characterize a series of VP40 mutants targeted to the molecular determinants of Ebola VP40 assembly and trafficking using confocal microscopy with genetically-encoded fluorescent tags. Using this approach, we characterize the subcellular distribution of these mutants, showing novel phenotypes for each. Mutants related to trafficking show aggregation dependent on membrane binding, suggesting a possible mode of VP40 Trafficking.