Efficient suilysin-mediated invasion and apoptosis in porcine respiratory epithelial cells after streptococcal infection under air-liquid interface conditions

Meng, Fandan; Wu, Nai-Huei; Seitz, Maren; Herrler, Georg; Valentin-Weigand, Peter

were used and all experiments were repeated three times. Well differentiated porcine airway epithelial cells (at least 5 weeks of differentiation) were maintained without antibiotic and antimycotics one day before infection and washed three times with phosphate-buffered saline supplemented with calcium (PBS+) before inoculation with S. suis. Well-differentiated epithelial cells were inoculated from the apical side of the filter with approximately 1 × 10 7 CFU of S. suis strain wt, 10Δ sly, 10Δ cpsΔ sly, cW461F, cS148 in 70 μ l ALI medium MOI of approximately 20 bacteria per epithelial cell), meanwhile, cells inoculated with ALI medium only served as mock infected cells. Infection was performed for 4 hours in humidified atmosphere containing 5% CO 2 at 37 °C. Afterwards, infected and mock infected cells were washed three times with PBS+ to remove non-adhered bacteria. All cells were maintained under ALI one space in between conditions for up to 72 hours in humidified atmosphere containing 5% CO 2 at 37 °C.