Ebola virus enters host cells by macropinocytosis and clathrin-mediated endocytosis.

Virus entry into host cells is the first step of infection and a crucial determinant of pathogenicity. Here we show that Ebola virus-like particles (EBOV-VLPs) composed of the glycoprotein GP(1,2) and the matrix protein VP40 use macropinocytosis and clathrin-mediated endocytosis to enter cells. EBOV-VLPs applied to host cells induced actin-driven ruffling and enhanced FITC-dextran uptake, which indicated macropinocytosis as the main entry mechanism. This was further supported by inhibition of entry through inhibitors of actin polymerization (latrunculin A), Na(+)/H(+)-exchanger (EIPA), and PI3-kinase (wortmannin). A fraction of EBOV-VLPs, however, colocalized with clathrin heavy chain (CHC), and VLP uptake was reduced by CHC small interfering RNA transfection and expression of the dominant negative dynamin II-K44A mutant. In contrast, we found no evidence that EBOV-VLPs enter cells via caveolae. This work identifies macropinocytosis as the major, and clathrin-dependent endocytosis as an alternative, entry route for EBOV particles. Therefore, EBOV seems to utilize different entry pathways depending on both cell type and virus particle size.