Fig. 1. Foldon-containing preF protein induces off-target responses in mice, NHPs and humans.
a, RSV-pre-exposed NHPs (n = 10) were immunized at week 0, week 60 and week 189 (arrows) with preF protein or preF protein–Ad26-preF. Foldon-binding antibody titres were measured using ELISA in serum isolated before immunization and 4 weeks after every immunization. b, Human participants were immunized with preF protein combined with Ad26-preF at week 0 and with preF protein or preF protein–Ad26-preF (blue symbols, n = 10) or Ad26-preF alone (orange symbols, n = 6) at week 52 (arrows). Just before and 2 weeks after immunization, foldon-binding antibody titres were measured using ELISA. c, Balb/c mice were immunized twice with a 4 week interval with AREXVY, an AS01E-adjuvanted preF-protein-based commercially available RSV vaccine (n = 6 per group) or buffer (n = 3). Foldon-binding antibody titres were measured using ELISA 2 weeks after the second immunization. End-point titres were calculated and expressed as log10. The bars represent mean titres per group. The NHP and human ELISAs have no lower limit of detection (LLOD) defined while the mouse ELISA has an LLOD of 1.47 (log10). NS, not statistically different. Statistical testing (two sided) was performed using paired t-test with Bonferroni correction (a), ANOVA with Bonferroni correction (b) or a Tobit model with Bonferroni correction (c).