Figure 1. Characterisation of the course of infection in cultured cells.

(A) Quantitative Western Blot showing the relative amounts of major viral structural proteins NP and VP40 released into cell culture supernatant during the indicated time periods. (B) Correlation of morphology and specific infectivity of MARV particles released into cell culture supernatant during the indicated time periods. Infectivity in each supernatant was determined in a TCID₅₀ assay and normalized for NP amounts in each supernatant to determine the specific infectivity (light grey areas). Relative amounts of filamentous virus (grey bars) and spherical virus (black bars) in each supernatant were determined by EM of thin sections. (C) Quantification of MARV-infected cell morphology over a 4-day infection period. HUH-7 cells were infected, fixed at the indicated time points, embedded in their in situ orientation and cell morphology was determined by EM of thin sections in a systematic random sampling manner. (D) Electron micrograph showing the intact morphology of an infected cell at day 1 p.i.. (E) 6 nm digital slice of a tomogram showing the periphery of an intact cell and the filamentous morphology of the viruses associated with the cell profile. (F) Quantification of morphology of cell-associated MARV particles over a 4-day infection period. Quantification was done as in C. (G) Vesiculated morphology of an infected cell at day 4 p.i.. (H) 8 nm digital slice of a tomogram showing the periphery of a vesiculated cell and the spherical morphology of two viruses and several cell-derived vesicles associated with the cell profile.