Testing therapeutics in cell-based assays: Factors that influence the apparent potency of drugs
The signal-to-noise ratio (Tecan plate reader) was determined for Vero E6 (A) cells at passage 6 and 28 and for Huh 7 (B) cells at passage 7 and 30. The cells were infected at different MOIs of EBOV/Mak for 48 h, then fixed and stained. The percentage of EBOV-positive cells (C, D) by HCI was determined in parallel. The S/N ratios were determined from the mean values (± SD, n = 3) of triplicate signal and noise wells. Values for % EBOV-positive cells were determined from triplicate wells (mean ± SD, n = 3). The data were derived from one individual experiment. Two-tailed paired t test was performed to compare the values for % of EBOV-positive cells between early and late cell passage in variable MOIs, which is significantly higher in early passage of than late passage in Vero E6 cells only. Abbreviations: EBOV, Ebola virus; HCI, high content imaging; Mak, Makona; MOI, multiplicity of infection; S/N, signal-to-noise.