Fig. 1: M2 specifically binds B7.1 and B7.2.
a–c The interactions of MPXV M2 with B7 ligands were evaluated by flow cytometry. Expi293 cells transiently transfected with human and mouse B7.1 or B7.2 (Expi293-hB7.1/2 or Expi293-mB7.1/2) were pre-incubated with the indicated concentrations of Bio-M2, and the cells were then stained with 0.2 μg/mL secondary streptavidin-APC antibody. The cells expressing corresponding B7 ligands stained with secondary antibody alone were used as a negative control (black). Representative flow cytometric curves were shown for MPXV Bio-M2 (a), VACV Bio-M2 (b), and CPXV Bio-M2 (c) (left). The average mean fluorescence intensity (MFI) from three (a) or two (b, c) independent experiments performed in duplicates is shown, and data in right panel of (a–c) are shown as mean or mean ± SEM (right). Gating strategy is shown in Supplementary Fig. 11a. d, e Quantitative analysis of the binding affinity of MPXV M2 to hB7.1/2 by BLI. The binding curves were obtained by immersing M2 immobilized sensors into serially diluted hB7.1/2 (d), or by immersing hB7.1/2 immobilized sensors into different concentrations of M2 (e). The sensors without M2 or hB7.1 loading were used in parallel to define the background. The BLI traces from one of three independent experiments are shown. The kinetic values were obtained by simultaneously fitting the association and dissociation responses to a 1:1 Langmuir binding model (KD, kinetic). Source data are provided as a Source data file.
