Fig 2.

Adhesion to and invasion of virus-free or swH1N1-infected NPTr cells by different strains of S. suis. NPTr cells were either preinfected with swH1N1 for 12 h (MOI, 1) or left untreated, and subsequently the cells were infected with S. suis strains (MOI, 10). (A) Adhesion (incubation time of 2 h) of different S. suis strains to NPTr cells. Results were determined after exposure of swH1N1-infected (V+B) or control (B) NPTr cells to S. suis, followed by extensive washing of nonadherent bacteria and cell lysis to obtain S. suis viable counts. (B) Invasion (incubation time of 1 h) of swH1N1-infected (V+B) or control (B) NPTr cells by different S. suis strains. Results were determined as described above, except that after washing, cells were exposed to antibiotics to kill extracellular bacteria. Table 1 describes the strains. Data are expressed as means ± standard errors of the means from at least four independent experiments, each done in triplicate. An asterisk indicates significant difference between samples infected with bacteria alone and those coinfected with virus and bacteria (P < 0.01).