Replication kinetics of Ebola virus (EBOV) and Marburg virus (MARV) in ferret cell lines. A–D, Ferret spleen (mpfSpleen), lung (mpfLung), heart (mpfHeart), and Vero E6 cells were inoculated with EBOV (A and C) or MARV (B and D) at an multiplicity of infection of 0.1; virus ribonucleic acid (RNA) within the supernatant was quantified by RT-qPCR (A and B), and infectious virus within the supernatant was quantified by median tissue culture infectious dose (TCID₅₀) (C and D) at 3, 7, and 14 days postinfection (dpi). Mean levels ± standard deviation of viral RNA in genome equivalents per mL (GEQ/mL) or mean tissue culture infectious dose per mL (TCID₅₀/mL) are depicted as histograms, with the individual technical replicates depicted as dots.