Figure 5
Comparative analysis of survival of different S. suis cps7 strains and a cps9 strain in blood of weaning and growing piglets ex vivo (A) and IgM-antibody titers of these piglets against cps7 (B) and cps9 (C). A Survival of S. suis strains was determined in porcine blood drawn from 5 piglets from a herd known to be free of S. suis cps7 and cps9 strains every week. Survival of S. suis cps7 strains 13-00283-02 and V2310/1 is significantly higher in weaning (4.5–6.5 weeks) than in growing piglets (7.5 and 8.5 weeks). The survival factor represented the ratio of CFU at 120 min to CFU at time zero. Bars and error bars represent mean values and standard deviations, respectively. IgM titers against inactivated cps7 S. suis strain 13-00283-02 (B) and cps9 S. suis strain 16085/3b (C) were measured in the same blood samples as used for the bactericidal assays. IgM titers rose significantly from weaned to 8.5 weeks-old piglets. Means and standard deviations are indicated by horizontal lines and error bars, respectively. Significant differences were determined using two-way ANOVA and subsequently Tukey’s multiple comparisons test (A) and one-way ANOVA with Dunn’s (B) or Tukey’s (C) multiple comparisons test respectively. Significances are indicated (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001).