Oral administration of glycyrrhizic acid with intramuscular injection of foot-and-mouth disease vaccine enhances the adaptive immune system

Figures

• 

  FIGURE 1. Oral administration of glycyrrhizic acid mediates early, and mid-term, and long-term immune responses in food-and-mouth disease (FMD)-vaccinated mice. Experiments were performed according to the mice experimental strategies described in 2.5, 2.6, 2.9, (see section “2 Materials and methods”) and Figure 1 panel (A). (A–E) Experimental strategy (A); SP O antibody titers (PrioCheck™ FMDV kit) (B); SP A antibody titers (PrioCheck™ FMDV kit) (C); VN titers for O PA2 (D); and VN titers for A YC (E). The horizontal dashed lines in panels (B,C) represent the manufacturer-specified threshold for a positive result. In panels (D,E), the dashed lines indicate a VN titer of 1:45 (equivalent to 1.65 on a Log10 scale), which is considered the minimum level required for protection against viral infection. Data are represented as the mean ± SEM of triplicate measurements (n = 5/group). Statistical analyses were performed using two-way ANOVA, followed by Tukey’s post-hoc test. *p < 0.05; **p < 0.01; ***p < 0.001; and ****p < 0.0001.

• 

  FIGURE 2. Oral administration of glycyrrhizic acid improves host protection against the virus in food-and-mouth disease (FMD)-vaccinated mice. Experiments were performed according to the mice experimental strategies described in 2.5, 2.7 (see section “2 Materials and methods”) and Figure 1 panel (A). (A,B) Survival rates post-challenge with O/VET/2013 (A); Changes in body weight post-challenge with O/VET/2013 (B). Data are presented as mean ± SEM of triplicate measurements (n = 5/group).

• 

  FIGURE 3. Oral administration of glycyrrhizic acid mediates early, and mid-term, and long-term immune responses in food-and-mouth disease (FMD)-vaccinated pigs. Experiments were performed according to the pigs experimental strategies described in 2.5, 2.8, 2.9, (see section “2 Materials and methods”) and Figure 3 panel (A). (A–E) Experimental strategy (A); structural protein (SP) O antibody titers (PrioCheck™ FMDV kit) (B); SP A antibody titers (PrioCheck™ FMDV kit) (C); virus neutralization (VN) titers for O PA2 (D); and VN titers for A YC (E). The horizontal dashed lines in panels (B,C) represent the manufacturer-specified threshold for a positive result. In panels (D,E), the horizontal dashed lines denote the VN titer of 1:45 (equivalent to 1.65 on a Log10 scale), which is considered the minimum level required for protection against viral infection. Data are represented as the mean ± SEM of triplicate measurements (n = 5/group). Statistical analyses were performed using two-way ANOVA, followed by Tukey’s post-hoc test. *p < 0.05; **p < 0.01; ***p < 0.001; and ****p < 0.0001.

• 

  FIGURE 4. Oral administration of glycyrrhizic acid increases the expression of secretory IgA. Experiments were performed according to the food-and-mouth disease (FMD)-vaccinated mice and pigs experimental strategies described in 2.5, 2.6, 2.8, 2.9, (see section “2 Materials and methods”), Figures 1, 3 panel (A). The concentration of murine and porcine secretory IgA (sIgA) were assessed in serum using a secretory IgA ELISA kit. (A,B) sIgA antibody titers in mice (Cusabio secretory IgA ELISA kit) (A); sIgA antibody titers in pigs (Cusabio secretory IgA ELISA kit) (B). Statistical analyses were performed using two-way ANOVA, followed by Tukey’s post-hoc test. **p < 0.01; and ****p < 0.0001.

• 

  FIGURE 5. Oral administration of glycyrrhizic acid induces the gene expression of systemic immune-related cytokines in food-and-mouth disease (FMD)-vaccinated pigs. Experiments were performed according to the pigs experimental strategies described in 2.5, 2.8, 2.10, (see section “2 Materials and methods”) and Figure 3 panel (A). (A–H) Gene expression levels of IL-2 (A); IL-4 (B), IL-12p40 (C); IL-17A (D); IL-18 (E); IL-23p19 (F); IL-23R (G); and IFNγ (H). Statistical analyses were performed using two-way ANOVA, followed by Tukey’s post-hoc test. *p < 0.05; **p < 0.01; ***p < 0.001; and ****p < 0.0001.