PTGS2 and infection: The immunofluorescence analysis of the villus-associated cells studied in the in vitro system showed that ECwt infection led to a significantly increased percentage of villus cells showing positive signals for the cellular proteins PPARγ, NF-κB, COX-2, and Hsc70 at 12 h.p.i., in comparison to that found in cells from uninfected control villi.