Fig. 3: MVA protection against MPXV challenge.

a Study design on NHP immunization and challenge periods in weeks, and a description of the four groups of cynomolgus macaques. One group was vaccinated before the challenge with two doses of MVA administered 4 weeks apart (MVA-PrEP, n = 4; gray). Another group was vaccinated with a single dose four days after the MPXV IIb challenge (MVA-PEP, n = 4; black). In addition, we challenged one group of convalescent NHPs previously exposed via the rectal or ID route alone or in combination 37–46 weeks before the challenge and described previously (Conv., n = 6; orange) and one control group (CTRL, n = 4; red). The four groups were challenged with 1 × 10⁷ pfu of MPXV by the rectal route as indicated in blue. MVA-PrEP animals were monitored during the MVA immunization phase, with blood samplings for immunogenicity analysis. Following the MPXV challenge, blood, rectal fluid, seminal plasma, and skin swab samples were collected. The blue vertical dotted line represents the challenge. The image was created in BioRender. Herate, C. (2025) https://BioRender.com/lkzvios. b Rectal fluids collected during the challenge phase were evaluated for viral DNA content by qPCR. Viral load is expressed as viral DNA copies/mL. Each graph represents the viral kinetics of one group during 27 days. The LLOD was 36,000 copies/mL and the LLOQ 100,000 copies/mL. c Rectal fluid containing viral DNA was tested for virus infectivity in Vero cells and measured in pfu/mL. The LLOD was established at 10 PFU/mL, indicated by the dotted line. All samples below the LLOD were considered negative and are represented by a value of 1. When qPCR was negative, samples were considered negative and are represented by a value of 1. d Area under the curve (AUC) of viral DNA in rectal fluids during the 27 days of follow-up and statistical analysis. (CTRL, n = 4; red), (MVA-PEP, n = 4; black) (MVA-PrEP, n = 4; gray) (Conv., n = 6; orange). **:p = 0.0079. Each circle represents one animal. e Viral load measured by qPCR in skin swabs (left) and seminal plasma (right) sampled at day 11 and statistical analysis. The mean value is represented by the horizontal bar. (CTRL, n = 4 for skin and seminal fluid; red), (MVA-PEP, n = 3 for skin and n = 4 for seminal fluid; black) (MVA-PrEP, n = 3 for skin and n = 4 for seminal fluid; gray) (Conv., n = 5 for skin and n = 6 for seminal fluid; orange). *:p = 0.0333. Each circle represents one animal. 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). Source data are provided as a Source Data file.