VIRURENCE FACTOR OF PATHOGENIC MARINE VIBRIOS

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Of the studies on virulence factors of pathogenic marine vibrios, that of Vibrio vulnificus has been well progressed within the two years. Results obtained in the first year are as follows: role of the capsular antigen in resistance of the vibrio against human serum bactericidal factors, hemolytic mechanism of V. vulnificus hemolysin (VVH) and purification of the protease (VVP) and its physiological roles in the infection. It was shown that hemolysis by VVH proceeded by means of colloid osmotic manner. The cholesterol-binding property of_VVH was used for preparation of specific antiserum against VVH by immunizing VVH-loaded cholesterol-liposome suspension. VVP was purified homogeneously and the enzymatic and physico-chemical properties were studied. VVP was a metaloprotease having a zinc atom per one VVP-molecule. VVP enhanced skin permeability by releasing histamine from mast cell and formation of bradykinin by activation of serum kallikrein-kinin system. In the second year, effect of serum alpha-2 macroglobulin (alpha-i-M) on VVP was studied. It was shown that alpha-2-M was the single metaloprotease-inhibitor in human serum and trapped VVP molecule by cleavage of the baite region. These results indicate that lopha-2-M is factor of host defense system against the vibrio infection. VVH also enhanced skin permeability by release of histamine, but the mechanism was different from that of VVP. VVP released histamine by exocytosis. whereas histamine release by VVH was due to cytolysis.