Fig. 4: Viral growth and attenuation of the Metavac®-RSV vaccine candidate in BALB/c mice.

BALB/c mice were infected by the IN route with 5 × 10⁵ TCID₅₀ of rHMPV virus, Metavac®, or Metavac®-RSV vaccine candidates. a Weight loss was monitored for 14 dpi (n = 16). Data are shown as means ± SEM. *p < 0.05, **p < 0.01, ***, p < 0.001 when compared to mock-infected mice using Repeated Measures Two-way ANOVA. b, c At 2 dpi, mice were euthanized, and BALs were harvested to measure HMPV-N gene (b) or RSV-F gene (c) copies by RT-qPCR (n = 2). d At 5 dpi, mean cumulative histopathological scores (peribronchial, intrabronchial, perivascular, interstitial, pleural, and intra-alveolar inflammation scores) of the lungs from infected mice were evaluated (n = 3). *p < 0.05, ***p < 0.001 when comparing mean global histopathological score to mock-infected mice using One-way ANOVA. e, f At 5 dpi, HMPV-N (e) or RSV-F (f) gene copies were measured by RT-qPCR from total RNA extracted from fixed lung tissues (n = 2–3). Data of viral gene quantification are shown as means ± SD.