Ebola virus uses tunneling nanotubes as an alternate route of dissemination.

Ebola virus disease is marked by the rapid virus replication and spread. Ebola virus (EBOV) enters the cell by macropinocytosis, replicates in the cytoplasm, and nascent virions egress from the cell surface to infect neighboring cells. Here, we show that EBOV uses an alternate route to disseminate: tunneling nanotubes (TNTs). TNTs, an actin-based long-range intercellular communication system, allows for direct exchange of cytosolic constituents between cells. Using live, scanning electron and high-resolution quantitative 3D-microscopy, we show that EBOV infection of primary human cells results in the enhanced formation of TNTs, containing viral nucleocapsids. TNTs promoted the intercellular transfer of nucleocapsids in the absence of live virus, and virus could replicate in cells devoid of entry factors after initial stall. Our studies suggest an alternate model of EBOV dissemination within its host, laying the groundwork for further investigations into the pathogenesis of filoviruses and, importantly, stimulating new areas of antiviral design.