FIG. 7.
Phagocytosis inhibition by pretreatment of J774 macrophages with purified CPS at 100 μg/ml or by preinfection with the S. suis type 2 encapsulated strain 735 (S.s) for 15 min before reinfection with S. suis nonencapsulated mutant 2A, GBS nonencapsulated mutant COH1-13, or GBS encapsulated parent strain COH1 (at 107 CFU/ml). Intracellular bacteria were recovered from cell lysates after 15 min of reincubation. The results are expressed as means ± the SD of the percent phagocytosis versus untreated control cells (1 × 104 CFU for strain 2A, 4 × 105 CFU for strain COH1, and 2 × 105 CFU for strain COH1-13; considered 100% phagocytosis in their respective histograms). An asterisk indicates a significant difference versus the phagocytosis values of untreated control cells (P < 0.05).