VIRURENCE FACTOR OF PATHOGENIC MARINE VIBRIOS

在致病性海洋弧菌毒力因子的研究中，创伤弧菌的研究在近两年来取得了较好的进展。第一年的研究结果如下：包膜抗原在弧菌抵抗人血清杀菌因子中的作用、创伤弧菌溶血素(VVH)的溶血机理、蛋白水解酶(VVP)的纯化及其在感染中的生理作用。结果表明，VVH的溶血是以胶体渗透方式进行的。利用VVH的胆固醇结合特性，免疫VVH胆固醇脂质体悬浮液，制备VVH特异性抗血清。对VVP进行了均一纯化，并对其酶学性质和理化性质进行了研究。VVP是一种金属蛋白酶，每个VVP分子中含有一个锌原子。VVP通过从肥大细胞释放组胺和通过激活血清激肽释放酶-激动素系统形成缓激肽来增加皮肤的通透性。第二年观察血清α-2巨球蛋白(α-I-M)对VVP的影响。结果表明，α-2-M是人血清中单一的金属蛋白水解酶抑制剂，通过切割Baite区捕获VVP分子。这些结果表明，LOPA-2-M是抗弧菌感染的宿主防御系统的因子。VVH也可通过释放组胺而增加皮肤通透性，但其机制与VVP不同。VVP通过胞吐作用释放组胺。而VVH的组胺释放是由于细胞溶解。

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.