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

Confluent epithelial cells at ALI conditions developed a TEER, indicating the development of tight junctions and an intact epithelial barrier 23 . The TEER of well-differentiated PTEC and PBEC, respectively, was measured before and after infection with S. suis by using the Millicell ERS-2 (Electrical resistance system, Millipore). For TEER measurement, both the apical and basolateral compartment of the transwell system were washed 3 times with PBS+ . Then 200 μ l ALI medium was added to the apical compartment while 500 μ l were added to the basolateral compartment. TEER across the multilayer of uninfected PTEC and PBEC was monitored from the first day after seeding cells on transwell filters over 40 days to characterize polarization and differentiation of PTEC and PBEC, respectively. After infection of cells with S. suis TEER was measured for at least 96 hpi.