Miyata Sarah T, Kitaoka Maya, Wieteska Lukasz, Frech Christian, Chen Nansheng, Pukatzki Stefan
Department of Medical Microbiology and Immunology, University of Alberta Edmonton, AB, Canada.
Front Microbiol. 2010 Nov 15;1:117. doi: 10.3389/fmicb.2010.00117. eCollection 2010.
Vibrio cholerae, the marine bacterium responsible for the diarrheal disease cholera, utilizes a multitude of virulence factors to cause disease. The importance of two of these factors, the toxin co-regulated pilus (TCP) and cholera toxin (CT), has been well documented for pandemic O1 and epidemic O139 serogroups. In contrast, endemic non-O1 and non-O139 serogroups can cause localized outbreaks of cholera-like illness, often in the absence of TCP and CT. One virulence mechanism used by these strains is the type VI secretion system (T6SS) to export toxins across the cell envelope and confer toxicity toward eukaryotic and prokaryotic organisms. The V. cholerae strain V52 (an O37 serogroup strain) possesses a constitutively active T6SS and was responsible for an outbreak of gastroenteritis in Sudan in 1968. To evaluate a potential role of the T6SS in the disease cholera, we compared the T6SS clusters of V. cholerae strains with sequenced genomes. We found that the majority of V. cholerae strains, including one pandemic strain, contain intact T6SS gene clusters; thus, we propose that the T6SS is a conserved mechanism that allows pandemic and endemic V. cholerae to persist both in the host and in the environment.
霍乱弧菌是一种引发腹泻疾病霍乱的海洋细菌，它利用多种毒力因子来致病。对于大流行的O1血清群和流行的O139血清群而言，其中两种因子，即毒素共调节菌毛（TCP）和霍乱毒素（CT）的重要性已有充分记载。相比之下，地方性非O1和非O139血清群通常在没有TCP和CT的情况下，也能引发类似霍乱疾病的局部暴发。这些菌株所使用的一种毒力机制是VI型分泌系统（T6SS），它可将毒素输出穿过细胞包膜，并对真核生物和原核生物产生毒性。霍乱弧菌V52菌株（一种O37血清群菌株）拥有一个组成型活性T6SS，并在1968年引发了苏丹的一场肠胃炎暴发。为了评估T6SS在霍乱疾病中的潜在作用，我们比较了具有测序基因组的霍乱弧菌菌株的T6SS基因簇。我们发现，大多数霍乱弧菌菌株，包括一个大流行菌株，都含有完整的T6SS基因簇；因此，我们提出T6SS是一种保守机制，它使大流行和地方性霍乱弧菌能够在宿主和环境中持续存在。
