CYP27A1 and vibrio infectious disease: CTX is the main virulence factor in toxigenic V. cholerae strains. It belongs to the AB5 family of toxins, which are composed of the catalytic A subunit (CTX-A) and the pentameric receptor-binding B subunit (CTX-B). These subunits are encoded by the ctxA and ctxB genes located in the filamentous bacteriophage CTXɸ (68). CTX is responsible for the secretory diarrhea characteristic of cholera. It is secreted through the type II secretion system (T2SS) and as cargo within outer membrane vesicles (OMVs) (69–72).