Distribution of genes for virulence and ecological fitness among diverse Vibrio cholerae population in a cholera endemic area:: Tracking the evolution of pathogenic strains
Distribution of genes for virulence and ecological fitness among diverse Vibrio cholerae population in a cholera endemic area:: Tracking the evolution of pathogenic strains
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DOI：
10.1089/dna.2008.0737
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发表时间：
2008-07-01
影响因子：
3.1
通讯作者：
Faruque, Shah M.
中科院分区：
文献类型：
--
作者：
Rahman, M. Hasibur;Biswas, Kuntal;Faruque, Shah M.
引起人类急性肠道感染的霍乱弧菌的致病性菌株来源于环境中的非致病性菌株。为了追踪致病性霍乱弧菌的进化并鉴定新致病性菌株的潜在前体，我们分析了324株环境或临床霍乱弧菌分离株，以确定是否存在与毒力或生态适应性相关的不同基因。在251株非O 1、非O 139环境菌株中，10株（3.9%）携带编码TCP的毒素协同调节菌毛（TCP）致病性岛和编码霍乱毒素的CTX噬菌体，而另外10株仅携带TCP岛，对CTX噬菌体的转导敏感。大多数霍乱弧菌O 1和O 139菌株携带这两个主要毒力决定因子，以及弧菌第七次大流行岛（VSP-1和VSP-2），而23（9.1%）非O 1，非O 139菌株携带几个VSP岛基因，但没有一个携带一个完整的VSP岛。相反，30株（11.9%）非O 1、非O 139菌株携带III型分泌系统（TTSS）基因，但检测的63株霍乱弧菌O 1或O 139菌株中无TTSS阳性。因此，主要毒力基因在非O 1、非O 139血清群霍乱弧菌中的分布与O 1或O 139血清群有很大不同。然而，推定的辅助毒力基因（mshA、hlyA和RTX）在所有菌株中的流行率相似，其中mshA最普遍（98.8%），其次是RTX基因（96.2%）和hlyA（94.6%），这支持了最近的假设，即这些基因赋予了增加的环境适应性。由于所有致病菌株都保留了这些基因，因此这些菌株的流行病学成功可能取决于它们在环境中的持久性以及产生主要毒力因子的能力。因此，新的致病菌株的潜在前体将需要组合生态适应性和毒性的基因，以获得流行病学优势。
The pathogenic strains of Vibrio cholerae that cause acute enteric infections in humans are derived from environmental nonpathogenic strains. To track the evolution of pathogenic V. cholerae and identify potential precursors of new pathogenic strains, we analyzed 324 environmental or clinical V. cholerae isolates for the presence of diverse genes involved in virulence or ecological fitness. Of 251 environmental non-O1, non-O139 strains tested, 10 (3.9%) carried the toxin coregulated pilus (TCP) pathogenicity island encoding TCPs, and the CTX prophage encoding cholera toxin, whereas another 10 isolates carried the TCP island alone, and were susceptible to transduction with CTX phage. Most V. cholerae O1 and O139 strains carried these two major virulence determinants, as well as the Vibrio seventh pandemic islands (VSP-1 and VSP-2), whereas 23 (9.1%) non-O1, non-O139 strains carried several VSP island genes, but none carried a complete VSP island. Conversely, 30 (11.9%) non-O1, non-O139 strains carried type III secretion system (TTSS) genes, but none of 63 V. cholerae O1 or O139 strains tested were positive for TTSS. Thus, the distribution of major virulence genes in the non-O1, non-O139 serogroups of V. cholerae is largely different from that of the O1 or O139 serogroups. However, the prevalence of putative accessory virulence genes ( mshA, hlyA, and RTX) was similar in all strains, with the mshA being most prevalent (98.8%) followed by RTX genes (96.2%) and hlyA (94.6%), supporting more recent assumptions that these genes imparts increased environmental fitness. Since all pathogenic strains retain these genes, the epidemiological success of the strains presumably depends on their environmental persistence in addition to the ability to produce major virulence factors. Potential precursors of new pathogenic strains would thus require to assemble a combination of genes for both ecological fitness and virulence to attain epidemiological predominance.