Ebolavirus is internalized into host cells via macropinocytosis in a viral glycoprotein-dependent manner

Ebolavirus (ebov) is an enveloped,single-stranded,negative-sense rna virus that causes severe hemorrhagic fever with mortality rates of up to 90% in humans and nonhuman primates. previous studies suggest roles for clathrin- or caveolae-mediated endocytosis in ebov entry; however,ebolavirus virions are long,filamentous particles that are larger than the plasma membrane invaginations that characterize clathrin- or caveolae-mediated endocytosis. the mechanism of ebov entry remains,therefore,poorly understood. to better understand ebolavirus entry,we carried out internalization studies with fluorescently labeled,biologically contained ebolavirus and ebolavirus-like particles (ebola vlps),both of which resemble authentic ebolavirus in their morphology. we examined the mechanism of ebolavirus internalization by real-time analysis of these fluorescently labeled ebolavirus particles and found that their internalization was independent of clathrin- or caveolae-mediated endocytosis,but that they co-localized with sorting nexin (snx) 5,a marker of macropinocytosis-specific endosomes (macropinosomes). moreover,the internalization of ebolavirus virions accelerated the uptake of a macropinocytosis-specific cargo,was associated with plasma membrane ruffling,and was dependent on cellular gtpases and kinases involved in macropinocytosis. a pseudotyped vesicular stomatitis virus possessing the ebolavirus glycoprotein (gp) also co-localized with snx5 and its internalization and infectivity were affected by macropinocytosis inhibitors. taken together,our data suggest that ebolavirus is internalized into cells by stimulating macropinocytosis in a gp-dependent manner. these findings provide new insights into the lifecycle of ebolavirus and may aid in the development of therapeutics for ebolavirus infection. © 2010 nanbo et al.