Fig. 7: Efficacy and immunogenicity of Metavac®-RSV vaccine candidate following RSV challenge.
BALB/c mice were immunized twice with a 21-day interval by the IN route with 5 × 105 TCID50 of Metavac®-RSV vaccine candidate or rRSV-mCh (RSV WT) virus. Three weeks after the last immunization, animals (n = 12/group) were inoculated with 1 × 105 PFU of rRSV-Luc virus. a, b Bioluminescence was measured at 3 and 5 dpc by IN injection of 50 µl of D-Luciferin (200 mM). a Ventral views of 4 representative mice were taken using the IVIS system. The scale on the right indicates the average radiance (a sum of the photons per second from each pixel inside the region of interest, ps-1 cm-2 sr-1). b Luciferase activities were quantified using ‘Living Image’ software and were represented as mean ± SEM photons per second (p/s) (n = 8/group). c, d RT-qPCR was performed on total RNA recovered from mouse lung homogenates (n = 4/group) harvested at 4 dpc to quantify RSV-F (c) or residual HMPV-N gene copies (d). e–g Immunogenicity of the Metavac®-RSV LAV candidate was measured by RSV A microneutralization assay, anti-total RSV or anti-preF RSV IgG ELISA assays from pools of sera (before each IN instillation at −1, 20, and 41 dpi) or individual sera (at the endpoint at 63 dpi, n = 6–8). e Neutralization of RSV A strain was represented as mean log2 reciprocal NAb titer. f, g IgG titer specific to RSV virus (f) or recombinant preF RSV protein (g) was represented as an arbitrary unit based on endpoint absorbance. Data are shown as means ± SD. *p < 0.05, **p < 0.01, ***p < 0.001 when comparing Metavac®-RSV or RSV WT vaccinated group to the mock-vaccinated condition using Two-way ANOVA.
