Bacterial proteases as pathogenic factors, with special emphasis on vibrio proteases

Bacterial proteases play various pathogenic roles in infection. Pathogenic species of the genus Vibrio, such as V. cholerae, V. parahaemolyticus or V. vulnificus also produce exocellular proteases, and almost of them are metalloproteases having a zinc atom. V. vulnificus is an opportunistic human pathogen causing septicemia or wound infections characterized by the formation of edema, necrotic ulcer and cellulitis on the skin. The protease produced by the vibrio (VVP) enhanced vascular permeability through activation of the Hageman factor-plasma kallikrein-kinin cascade and/or exocytotic histamine release from mast cells, and formed hemorrhagic lesions which subsequently provoke severe dermonecrosis. Thus, VVP is the most probable candidate for edema formation in the infection. Other pathogenic roles of VVP were also demonstrated. The VVP gene was cloned, and the amino acid sequence was deduced from the nucleotide sequence. The mature protein was demonstrated to be composed of 413 amino acid residues and showed 69 to 74% homology with other vibrio proteases.