Fig. 1. Identification of two neutralizing antibodies from the phage-display library.

a Binding curve of two clones to NiV-RBP. Both FabNiV41 and FabNiV42 could specifically bind to the NiV-RBP. b Kinetic binding curves for antibody–antigen interactions were determined by BLI. Biotinylated RBPs were loaded onto probes, while serial dilutions of Fab fragments were then associated with coated probes. K_on, association rate constant; k_dis, disassociation rate constant; K_D, equilibrium dissociation constant. c Blockage of NiV-RBP-Fc binding to Vero cells by Fabs as measured by flow cytometry. Cells were stained with NiV-RBP pre-incubated with NiV41 and NiV42. d Binding curve of NiV41 and NiV42 to RBPs. After converted to IgG format, the binding ability of NiV41 and NiV42 to henipavirus RBPs were detected by ELISA. e Neutralization activity evolution of antibodies against NiV and HeV pseudovirus. To determine the half-maximal inhibitory concentration (IC₅₀), a sigmoidal dose-response curve was applied to the GFP-positive cells or luciferase activities exposed to serially diluted antibody. f Neutralization of authentic henipavirus in Vero E6 cells, measured in a plaque reduction neutralization assay. The mixtures of virus and serially diluted NiV41 or NiV42 were added to Vero E6 cells. After 72 h incubation, IC₅₀ were calculated by fitting the number of plaques with serially diluted antibody to a sigmoidal dose-response curve. g Therapeutic efficacy of NiV41 against a lethal challenge with the NiV_B strain. Hamsters were treated with 3 mg/kg NiV41 or PBS 6 h after intraperitoneal inoculation with NiV. The survival data were collected daily for 28 days after inoculation (day 0). Data (n = 6 biologically independent animals per group) were analyzed by the two-sided log-rank (Mantel‒Cox) test (*p < 0.1). MST, median survival time. Data were represented as the mean ± S.D. from n = 3 biologically independent experiments. (a, c–f). Source data are provided as a Source Data file.