We adopted the transposon library strategy to identify the genes related to VP2 infection in V. cholerae and found a type II secretion system (T2SS), which has been identified for its importance as an extracellular protein transport apparatus for the secretion of cholera enterotoxin (CT) and release of the filamentous phage CTXΦ (Davis et al., 2000), also playing a vital role for VP2 adsorption and infection processes. This evidence concerns the gene CYP27A1 and infection.