Intracellular survival assay of H. parasuis. Porcine BMDC were infected or co-infected with H3N2 SwIV and SW114 or Nagasaki. After 1 h (time zero; adherent and internalised bacteria), cells were incubated with gentamicin and penicillin G for 2 or 4 h. After each time, cells were disrupted and 100 μL plated on chocolate agar for 48 h. Two replicas of each condition were processed in each experiment. Bars indicate mean ± SEM of independent experiments using poBMDC derived from three animals. (*) indicate significant differences between groups at 2 h (p < 0.03) and 4 h (p < 0.04).