HapA is a Zn-dependent metalloprotease secreted through the T2SS as a free protease or in a cell-associated form (73). HapA exhibits several proteolytic activities, including modifying toxins and degrading mucin, fibronectin, and lactoferrin (91). It also acts on TJ-associated proteins, disrupting the paracellular barrier function (92). HapA promotes penetration of the mucosal layer, as well as detachment and spreading of infection along the gastrointestinal tract (93). This evidence concerns the gene LTF and infection.