Changes in the motif structure of the CagY middle repeat region that alter the function of the <i>cag</i>PAI do not affect expression of T4SS pili on the bacterial surface.

<p><i>H. pylori</i> was co-cultured with AGS gastric cells at an MOI of 100∶1 and imaged by FEG-SEM. T4SS pilus structures were readily apparent in the WT <i>H. pylori</i> J166 but not in the <i>cag</i>PAI deletion mutant (J166▵<i>cag</i>PAI). T4SS pili were also observed in <i>H. pylori</i> J166 in which the WT <i>cagY</i> allele was replaced with that from output strains with a functional (rOut3, mOut3) or a non-functional (rOut2 mOut2) <i>cag</i>PAI. Pili were also seen in <i>H. pylori</i> strains J166 and 26695 with deletions in <i>cagY</i>. Magnification bars indicate 500 nm.