Fig. 5: CV3-25 binds to stem helix peptides from diverse betacoronaviruses but only to cell surface-expressed sarbecovirus spike proteins.

Binding of CV3-25 (a), B6 (b), CC40.8 (c) or the inferred germline version of CV3-25 (d), to linear peptides from SARS-CoV-1/2/WIV1, MERS-CoV, HCoV-OC43, and HCoV-HKU1 was measured by ELISA. Each dot represents a technical replicate measured in duplicate in (a–d). Spike proteins from SARS-CoV-2 Wuhan-Hu-1 (e), SARS-CoV-1 Urbani (f), WIV1 (g), HCoV-HKU1 (h) and HCoV-OC43 (i) and MERS-CoV (j) spike proteins were expressed on the surface of 293 cells, and then stained with the indicated fluorescently labeled mAbs and then analyzed by flow cytometry. The percentage of cells that stained positive with the mAbs is indicated on the y axis. One representative example of two independent experiments with three technical replicates is shown. Neutralization of authentic OC43 by CV3-25 IgG or Fab (k), or human sera (l). m Neutralization of MERS-CoV pseudovirus by the indicated mAbs. Each dot represents a technical replicate from one or two experiments conducted in duplicate in (a–m). Bars represent the mean and error bars represent the standard deviation in (e–j).