Fig 1.

Adhesion to and invasion of virus-free or swH1N1-infected NPTr cells by S. suis serotype 2 strain 31533. NPTr cells were either preinfected with swH1N1 for 12 h (MOI, 1) or left untreated, and cells were subsequently infected with S. suis serotype 2 strain 31533 (MOI, 10). (A) Kinetics of adhesion of S. suis to virus-infected (V+B) or control (B) NPTr cells. After S. suis infection, cells were extensively washed to remove nonadherent bacteria and then lysed to determine S. suis viable counts. (B) S. suis invasion of swH1N1-infected (V+B) or control (B) NPTr cells at bacterial incubation times of 2 and 4 h. Results were determined as described above, except that after washing, cells were exposed to antibiotics to kill extracellular bacteria. Data are expressed as means ± standard errors of the means from at least four independent experiments, each done in triplicate. An asterisk indicates significant differences between samples infected with bacteria alone and those coinfected with virus and bacteria (P < 0.01).