Extended Data Fig. 6: Normalized S-curves for determining the PRNT50 MVA-H5 sera.

(a) Sera were 2-fold diluted starting at a dilution of 1:10 in duplicate, followed by the addition of rMVA-GFP suspension (a) or MPXV suspension (b) leading to ± 500 plaques/well in infection controls. Percentage plaque reduction compared to the infection control was calculated per dilution and plotted as log (inhibitor) vs response curve with four parameter variable slope using GraphPad Prism 9.02. The dilution that would yield 50% reduction of plaques compared to the infection control was estimated by determining the proportionate distance between two dilutions, from which an endpoint titer was calculated. PRNT50 values are shown in Fig. 2e for MVA-GFP and Fig. 2f for MPXV. Symbols indicate individual donors, cyan lines represent sera from MVA-H5-vaccinated donors. All samples from this serum panel were run in the same ELISA or PRNT experiment, avoiding any possible batch effects.