引用本文:	潘海建,郝斌,李杰,李贵阳,肖鹏,莫照兰.Cpx 对迟缓爱德华氏菌毒力的影响[J].海洋科学,2013,37(2):17-21.

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Cpx 对迟缓爱德华氏菌毒力的影响
潘海建^1,2, 郝斌^1,2, 李杰^1,3, 李贵阳^1,3, 肖鹏¹, 莫照兰^1,3
1.中国科学院海洋研究所实验海洋生物学重点实验室;2.中国科学院研究生院中国水产科学院;3.黄海水产研究所海水养殖生物疾病控制与分子病理学实验室

摘要:

迟缓爱德华氏菌(Edwardsiella tarda)是水产养殖动物常见病原菌。接合质粒表达系统(conjugativeplasmid expression, Cpx)是G–菌的双组分调控系统。本研究构建了迟缓爱德华氏菌LSE40 的cpx基因簇缺失突变株Δcpx, 检测其对蓝曼龙(Trichogaster trichopterus)的毒力。结果显示以浸泡感染, Δcpx的毒力有所降低。以肌肉注射途径感染, Δcpx的半数致死量为8.6×10⁵ cfu/mL 毒力下降7.33 倍。Δcpx在鱼体内的生存力显著下降(P<0.05)。这些结果表明Cpx 参与了迟缓爱德华氏菌的致病作用。

关键词: 迟缓爱德华氏菌(Edwardsiella tarda)LSE40 Cpx 毒力

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基金项目:国家自然科学基金资助项目(192832); 国家科技计划社会发展科技领域项目(2011BAD13B07); 青岛市科技发展计划项目(08-1-7-2-HY)

Impact of Cpx on the virulence of Edwardsiella tarda

Abstract:

Edwardsiella tarda is a gram-negative bacterium that can cause edwardsiellosis diseases in marine and fresh water fish, resulting in considerable economic losses in aquaculture. Function of the Cpx (conjugative plasmid expression) regulatory system in E. tarda is not clarified. In this study, the cpx cluster in-frame deletion mutant was constructed from E. tarda LSE40 and its virulence was determined. The blue guorami fish Trichogaster trichopterus was infected with wild-type or Δcpx mutant by immersion or intramuscular injection (i.m.). In the immersion route, virulence of the Δcpx mutant showed certain defect compared with wild-type strain; in the i.m. route, the Δcpx mutant exhibited 7.33-fold decrease with a median lethal dose of 8.6×10⁵ cfu/mL. Bacterial counts in the liver of fish i.m. infected with the Δcpx mutant were evidently lower than the fish infected the wild-type strain. These results indicated that Cpx was involved in the virulence of E. tarda.

Key words: Edwardsiella tarda Cpx virulence