Fig 5.

S. suis native, but not desialylated, capsular polysaccharide (CPS) inhibits S. suis adhesion to (A) and invasion of (B) NPTr cells preinfected with swH1N1. NPTr cells were infected with swH1N1 (MOI, 1) for 12 h and then incubated with the native CPS (100 μg/well), desialylated CPS (100 μg/well), or a polyclonal antibody serum against SIV H1N1 (1/40 dilution; positive control) for 1 h at 37°C. S. suis strain 31533 (MOI, 10) was then added to pretreated NPTr cells. Two hours postinfection, adhesion and invasion of S. suis were assessed as described in Materials and Methods. Results are expressed (in percentages) compared to bacterial adhesion and invasion of untreated swH1N1-preinfected cells (considered 100%). Data are expressed as means ± standard errors of the means from at least three independent experiments. Groups that are significantly different from each other are indicated by different letters (a and b), as determined by one-way ANOVA with P ≤ 0.01.