As for flagellin, the absence of TLR5 transcript observed either with PS cells or primary MEC, along with the weak response induced by purified flagellin, are in agreement with previous in vitro and in vivo studies that suggest that flagellin is not a major contributor to the inflammatory response of the udder to E. coli infection [16,44]. This evidence concerns the gene TLR5 and escherichia coli infection.