MARV infections usually occur by direct contact with infected body fluids or direct personal contact with infected animals or humans. The viruses enter the body through small skin lesions or mucosal membranes (reviewed in [47] ). Cells of the mononuclear phagocyte system, including monocytes, macrophages and dendritic cells, are early target cells of MARV, as shown in different experimental animal models [14, [192] [193] [194] [195] [196] [197] . MARV replication was observed as early as 24 hours post infection in macrophages of infected guinea pigs [63] , and infected monocytes have been found in cynomolgus macaques at 2 days post infection [193] . Monocytes and macrophages were also identified as early target cells in human patients [197] . This has been confirmed by cell culture experiments showing that primary human monocytes and macrophages are highly susceptible to MARV infection and produce infectious virus [198] [199] [200] . In addition, primary human monocyte-derived dendritic cells (mDCs) and endothelial cells support MARV replication [64, 146, 201] .