CLDN4 and infection: Since the diminished membrane-bound CLDN-4 expression in Ct-infected pOEC could not be explained by an overall downregulation of CLDN-4 mRNA or protein expression, we performed a series of Ct-infection time kinetics with a focus on confocal microscopy analysis of the location of CLDN-4 within pOECs: we infected pOEC lines from three pigs with MOCK or Ct followed by the same Ct, DAPI, and CLDN-4 staining and downstream confocal imaging analysis as used in Figure 1A. The progression of Ct infection can be tracked by the increase in the size of Ct inclusions (Figure 7A).