Ebola and Marburg viruses: I. Some ultrastructural differences between strains when grown in Vero cells

A strain of Marburg virus and two strains of Ebola virus grown in Vero cells were compared by electron microscopy. The outer coat of the Marburg virion appeared to be more resistant to erosion by negative staining techniques than that of the Epbola strains. Marburg virus commonly produced "torus" forms and short filaments; the Zaire strain of Ebola produced extensive branched forms and very long filaments; the Sudan strain of Ebola produced shorter, less branched structures but very many aberrant forms. The mechanism for the production of these aberrant forms is described.