Figure 1. Evolutionary tree of the family Filoviridae based on the coding regions of glycoprotein gene sequences. Branch lengths correspond to nucleotide differences between virus isolates for which transversions have been weighted 4:1 over transitions.

Figure 2. Scanning electron micrograph of a cultured monkey kidney cell infected with a Zaire species of Ebola virus. Virions are seen budding from the entire surface of the cultured cell. Courtesy of C S Goldsmith, Centers for Disease Control and Prevention, Atlanta.

Figure 3. Representation of a filovirus virion depicting the locations and associations of the structural proteins with the genomic RNA or outer membrane. The ribonucleoprotein complex (nucleocapsid) is surrounded by a lipid bilayer derived from the outer cell membrane. VPn, virion protein of nkDa molecular size.

Figure 4. Representation of a cell showing the replication of a filovirus in the cytoplasm of a cell. Depicted from left to right are the binding and entry of an infecting virion, virus protein expression and RNA replication, and the assembly and release of a new virion. The ‘+’ and ‘–’ signs indicate the sense of the RNA in nucleocapsids or messenger RNA. Ebola viruses differ from Marburg virus in that the former produce a nonstructural, secreted glycoprotein (SGP) in addition to the seven structural proteins.