Figure 4.

Neutralizing anti-CPB antibody titers determined by cell culture assay. (a) Progression of neutralizing antibody titers determined by cell culture assay in sow serums. B0: before the initial immunization, B1: after first immunization, B2: after second immunization, B3: before booster vaccination during 2nd pregnancy, B4: after booster vaccination during 2nd pregnancy. Asterisks indicate significant differences between groups (repeated measures ANOVA, Tukey–Kramer Multiple-Comparison test). Antibody titers significantly increased from B1 to B2 (p < 0.01), decreased from B2 to B3 (p < 0.05) and increased again after the booster immunization from B3 to B4 (p < 0.01). Antibody titers after the second pregnancy (B4) were significantly higher than after the first (B2) (p < 0.01). (b) Neutralizing colostral antibody titers after first (1) and second (2) farrowing determined by cell culture assay. Titers after the second farrowing were significantly higher (asterisks) compared to the first farrowing (p < 0.05) (repeated measures ANOVA, Tukey–Kramer Multiple-Comparison Test). (c) Progression of neutralizing antibody titers in piglet serums one (P-B1), two (P-B2), three (P-B3) and four weeks p.p. (P-B4) determined by cell culture assay. Asterisks indicate significant differences between groups (repeated measures ANOVA, Tukey–Kramer Multiple-Comparison test). Mean antibody titers of the second litter were significantly higher compared to the first litter in the vaccinated groups (p < 0.01 for all time points). No neutralizing antibodies were detected in the non-vaccinated group. (d) Scatterplot and linear regression model (continuous line, equation in results) of neutralizing antibody titers in vaccinated sows in serum p.p. of the second litter and colostrum determined by cell culture assay. Units: Log(IU/mL + 0.01). Each dot represents samples from one litter. One sow did not gain antibodies (value at lower left corner).