Figure 9.

Experiment 2: Opsonophagocytosis killing of S. suis serotype 7 induced by serum antibodies from sows and from their piglets. Blood samples were collected one week before farrowing from seven vaccinated and seven non-vaccinated sows and from randomly chosen piglets (1 per sow) at one and five weeks of age (n = 20 per group) to evaluate their functionality in an opsonophagocytosis assay (OPA). For OPA, blood leukocytes were mixed with S. suis serotype 7 (vaccine strain) at a multiplicity of infection of 0.01. Control sera or sample sera from vaccinated or non-vaccinated animals were added to a final concentration of 40% v/v in microtubes, which were incubated for 4 h. After incubation, viable bacterial counts were performed and the percentage of bacterial killing determined. The results are expressed as percent of bacterial killing for individual sera, with horizontal bars representing mean ± SEM. Values significantly different are shown in the graph with corresponding p value.