Fig. 4: MVA vaccine and MPXV challenge immunogenicity.

a The concentrations of five MPXV (upper panel) and homologous VACV (lower panel) protein-binding IgG were quantified in the serum of NHPs that were either immunized with MVA and/or challenged with MPXV. The data are expressed in arbitrary units (arb. unit./mL). Total IgG concentrations in NHP serum were monitored during the immunization phase for the MVA-PrEP group and after the challenge phase. For the remaining three groups, IgG follow-up began two weeks prior to the challenge. b Seroneutralization titers were measured in the serum collected at week -1 and week 4 post-challenge using Vero cells and live MPXV or VACV. The mean PRNT50 with standard deviation were calculated using infectious MPXV IIb (left panel): *:p = 0.0159, MPXV Ia (middle panel): *:p  = 0.0159 or VACV-107 (right panel): *:p = 0.0190 and **:p = 0.0095. (CTRL, n = 4; red), (MVA-PEP, n = 4; black), (MVA-PrEP, n = 4; gray), (Conv., n = 6 at W-1 and n = 5 at W4; orange). c, d Cellular immunity conferred by MVA vaccination and/or MPXV challenge. (CTRL, n = 4; red), (MVA-PEP, n = 4; black) (MVA-PrEP, n = 4; gray) (Conv., n = 6 and n = 5 from W14; orange). Intracellular staining of PBMCs, collected during the MVA immunization phase and after MPXV challenge, after an overnight MPXV or MVA stimulation in vitro. Panels represent the mean percentage with standard deviation of CD4⁺ CD154⁺ cells expressing IFN-γ (c) and IL17A (d) upon MPXV 2b (left) or MVA (right) stimulation. For (b–d), each circle represents one animal. When represented, statistical analyses were performed using the Kruskal-Wallis test followed by a two-tailed non-parametric Mann-Whitney test (*p < 0.05, **p < 0.01). Ag: antigen; Stim. Stimulation. Source data are provided as a Source Data file.