Fig. 7: Binding affinities, neutralization activities and therapeutic efficacy of the chimeric MAbs.

a Schematic of chimeric MAb. Mouse variable domains are shown as red boxes, while human constant domains are shown as green boxes. b SDS-PAGE and western blotting analysis of the purified MAbs. Lane M, protein marker; m2H12, murine MAb 2H12; m8F12, murine MAb 8F12; c2H12, chimeric MAb 2H12; c8F12, chimeric MAb 8F12. Anti-human IgG or anti-mouse IgG secondary antibodies (HRP conjugate) used in this study recognize the constant domains of both heavy (HC) and light chains (LC). c, d Binding affinities of the chimeric MAbs c2H12 (c) and c8F12 (d) to EV-D68 18947 virion measured by BLI. MAb concentrations used were shown. e Comparison of neutralization activities of the chimeric (c2H12 and c8F12) and murine (m2H12 and m8F12) MAbs against EV-D68 strain 18947. The method was described in the legend of Fig. 1. Result shown is representative of three independent experiments. f Characteristics of chimeric MAbs. KD values for the interaction of the MAbs with EV-D68 18947 virion were determined by BLI as described in panels (c, d) and Fig. 1d, e. Half inhibitory concentration (IC50) of each antibody was calculated using GraphPad Prism software and results represent the mean ± SD of three independent experiments. Neut., neutralization. g, h Therapeutic efficacy of chimeric MAbs against EV-D68 infection in neonatal mice. One-day-old ICR mice (n = 14–15/group) were inoculated i.p. with strain 18947. The suckling mice were i.p. injected with PBS, 10  µg/g of c2H12, or 10 µg/g of c8F12 at 1 dpi. Red arrow indicates time of MAb administration. Clinical scores were graded described in Fig. 2 legend. Survival of mice in each antibody-treated group was compared to the PBS control group. Statistical significance was determined by Log-rank (Mantel-Cox) test and was indicated as follows: ****, p < 0.0001. In panel (g), p value between the c2H12 or c8F12 group and the PBS control group is below 0.0001. Error bars represent SEM.