Fig. 2: Vaccines’ protection from a challenge with the Gamma VOC.

Transgenic mice vaccinated at day −28 were challenged with Gamma at day 0. At day +4 postchallenge, 7 mice of each group were euthanized and all the organs were removed (a). Samples of lungs and brains were used to assess viral load by quantitative PCR of gE (b and d) and sgE (c). The rest of the mice were followed to assess weight changes after the challenge (e). Immunopathological analysis of the lungs of unvaccinated mice show (f) interstitial pneumonia (IN), (g) inflammatory cells (IC), and (h) loss of epithelial cells (LE) and hyperplastic bronchiole (HB) that were used to obtain the pathology score (i). Staining of N protein in lungs of unvaccinated (j and l) and vaccinated mice (k and l) and CD + 3 infiltrate in unvaccinated (m and o) and vaccinated mice (n and o) is also shown. Similar studies on unvaccinated mice brains at day 6 show intraneural inclusion bodies (arrow heads), neuronal necrosis (NN), tigrolysis (T) and lymphoplasmacytic cuffing (LC) (p and q); the pathology score in the brain is also shown (r); staining of N protein in unvaccinated (s and u) and vaccinated mice (t and u) and CD3+ cells staining in unvaccinated (v and x) and vaccinated mice (w and x) is also shown. Number of mice analyzed: unvaccinated mice at day 4 (n = 7) and at day 6 (n = 8); all the groups of vaccinated mice: at day 4 (n = 7) and at day 14 (n = 8); naïve mice ranged between 3-4 mice for viral load and histological studies. Image scale bars represents approximately 250 μm for low magnification and 25 μm for 400X images. Differences between experimental groups in b, c and d were analyzed by Kruskal–Wallis test followed by Dunn’s multiple comparisons. Two-way ANOVA with Dunnett a posteriori was performed for e. Data is presented as mean standard error of the mean (SEM). *p < 0.05, **p < 0.01, ***p < 0.001 vs unvaccinated mice. The box plots in b, c, d, i, l, o, r, u and x show the median, 25th and 75th percentiles, and the whiskers show the range.