Mechanism and epidemiological significance of high contaminations of Vibrio parahaemolyticus to estuarine molluscs

根据我们在桥口湾的两种软体动物中检测到高水平的副溶血性弧菌，并在免疫扩散中检测到许多菌株为神奈川阳性，推测副溶血性弧菌与河口软体动物之间存在密切的关系。因此，研究了副溶血性弧菌D-3（神奈川阳性）、R-13（神奈川阴性）和大肠埃希菌YS-2在这些饲养的软体动物中的存活情况。这些菌株在逆转录梭菌中存活21天。菌株D-3和R-13在粳稻中存活14 d， YS-2不存活。这些菌株在72小时内从海洋软体动物白海绵中被消灭。建立了用酶联免疫法从副溶血性弧菌培养上清液中检测神奈川溶血素的方法。煮沸30分钟使上清液中的抑制物失活。在河口菌株的煮沸上清液中，36株逆转录弧菌中检出9株溶血素，35株日本弧菌中检出21株溶血素，其滴度在40 ~ 80单位/ml之间，而临床分离株的滴度为1280单位/ml。由于副溶血性弧菌菌株在河口软体动物体内的成功定殖被认为是源于软体动物血细胞的缺陷反应，因此在盲孔室中测量了血细胞对菌株D-3、R-13和YS-2的趋化反应。白念珠菌的血细胞对所有菌株都有积极的迁移，而逆行念珠菌的血细胞对任何生物体都没有迁移。在粳稻血细胞中，黏附细胞不向任何生物迁移，而非黏附细胞只向YS-2迁移。

From our evidences that high levels of Vibrio parahaemolyticus were detected from two molluscs, Clithon retropictus and Corbicula japonica, at Hashizu estuary and that many strains detected from C. retropictus were estimated as Kanagawa-positive in immunodiffusion, close relationships between V. parahaemolyticus and estuarine molluscs were suspected. Thus, survivals of V. parahaemolyticus D-3 (Kanagawa-positive) and R-13(Kanagawa-negative) and Escherichia coli YS-2 in these molluscs held in aquaria were investigated. These strains survived in C. retropictus for 21 days. Strains D-3 and R-13, but not YS-2, survived in C. japonica for 14 days. These strains were eliminated from Nerita albicilla, a marine mollusc, within 72 hours.Method to detect Kanagawa hemolysin from culture-supernatants of V. Parahaemolyticus strains utilizing enzyme-linked immunoassay was developed. inhinitor(s) in the supernatants was inactivated by boiling for 30 min. Among boiled-supernatants of estuarine strains, the hemolysin was detected from 9 strains in 36 strains derived from C. retropictus and from 21 in 35 derived from C. japonica, whose titers were between 40 and 80 units/ml compared with 1280 units/ml in clinical isolates.As successful colonizations of V. parahaemolyticus strains in the estuarine molluscs was supposed to be derived from defective responses of the molluscan hemocytes, chemotactic responses of the hemocytes to strains D-3 R-13 and YS-2 were measured in blind well chambers. Hemocytes of N. albicilla showed an active migration to all strains while those of C. retropictus showed no migration to any organisms. Of C. japonica hemocytes, adhesive cells showed no migration to any organisms while non-adhesive cells migrated only to YS-2.