溶珊瑚弧菌hapR基因的敲除及功能研究

溶珊瑚弧菌(Vibrio coralliilyticus)是多种珊瑚的致病菌。hapR是弧菌群体感应系统核心的泛调控基因。前期实验中发现，溶珊瑚弧菌在感染佳丽鹿角珊瑚时，致病力与其接种密度密切相关，推测溶珊瑚弧菌的群体感应系统可能是调控其毒力的关键因子。笔者利用同源重组技术成功构建了溶珊瑚弧菌hapR缺失株△hapR-Vc450和回补株ChapR-Vc450，表型测试结果表明，hapR的缺失影响溶珊瑚弧菌的菌落形态，但不影响细菌的运动性和鞭毛结构；hapR缺失后，细菌最大生长量明显减少，但生物膜的形成量显著增加；用溶珊瑚弧菌人工感染鹿角珊瑚，结果显示，hapR缺失后菌株毒力增加，表明hapR在溶珊瑚弧菌中可能具有与霍乱弧菌hapR相似的功能，可以抑制毒力基因的级联激活。

Knockout and Functional Analysis of hapR in Vibrio coralliilyticus

Vibrio coralliilyticus is pathogenic to many species of marine animals. HapR is a global regulator in Vibrio quorum sensing system. Our previous experiment showed that the pathogenicity of V. coralliilyticus was closely related to its inoculating concentration when Acropora species were infected with V. coralliilyticus under an artificial condition. Therefore, quorum sensing system of V. coralliilyticus is presumed to be essentially associated with its virulence. In this study, a deletion mutant strain △hapR-Vc450 and a complementary strain ChapR-Vc450 were successfully constructed in V. coralliilyticus. Phenotypic observation showed that loss of hapR resulted in change of colony morphology but not in the motility and flagellar structure of V. coralliilyticus. The loss of hapR caused lower maximum growth of V. coralliilyticus, but obvious formation of biofilm. When Acropora species was artificially infected with V. coralliilyticus, the deletion mutant strain and the complementary strain of V. coralliilyticus increased their virulence as compared with the wild type. This may be due to the fact that hapR has a similar function in V. coralliilyticus like in V. cholera, inhibiting cascade activation of virulence genes, and that the loss of hapR would activate the colonization and virulence of the genes through quorum sensing system.