Figure 5

Protective efficacy of CRM-conjugated combination vaccines against CovR/S WT and hypervirulent GAS. Cohorts of BALB/c mice were immunised intramuscularly with either MJ8-CombiVax or individual vaccine components. An additional cohort immunised with J8-CRM + S2-CRM was also included for comparison. Two weeks following last immunisation, the mice were challenged via the skin route of infection with two different GAS strains, NS1 (A–C), or NS88.2 (D–F). On days 3 and 6 post infection, 5 mice/group were sacrificed and samples were collected to determine bacterial burden. Percent reduction in skin, blood and spleen bacterial burden in comparison to the naïve challenge control (n = 5/group) was calculated and is shown as mean ± SEM. The mean bacterial burdens for NS1 GAS in control mice were 5115000 and 41850 (skin); 34440 and 22200 (blood); 522240 and 59450 (spleen) on days 3 and 6 respectively. For NS88.2 GAS, the mean bacterial burdens in control mice were 6695000 and 2045000 (skin); 77750 and 52460 (blood); 890700 and 731400 (spleen) on days 3 and 6 respectively. Statistical analysis was performed using one-way ANOVA with Tukey’s multiple comparison tests to compare each group with every other group at each time point. ns, p > 0.05; *p < 0.05; **p < 0.01.