Legionella pneumophila strain associated with the first evidence of person-to-person transmission of Legionnaires' disease: a unique mosaic genetic backbone.
Legionella pneumophila strain associated with the first evidence of person-to-person transmission of Legionnaires' disease: a unique mosaic genetic backbone.
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DOI：
10.1038/srep26261
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发表时间：
2016-05-19
影响因子：
4.6
通讯作者：
Gomes JP
中科院分区：
文献类型：
--
作者：
Borges V;Nunes A;Sampaio DA;Vieira L;Machado J;Simões MJ;Gonçalves P;Gomes JP
最近报告了军团病人际传播的第一个有力证据。在这里，我们对该病例相关的嗜肺军团菌菌株（“PtVFX/2014”）的遗传主干进行了表征，该菌株也导致了LD的大规模暴发。PtVFX/2014与世界上研究最多的与暴发相关的嗜肺军团菌亚种嗜肺血清1组菌株在系统发育上存在差异。事实上，该菌株也来自血清1群，但属于嗜肺乳杆菌亚种。它的基因组马赛克骨架揭示了8个水平转移的区域，包括涉及脂多糖生物合成或编码毒力相关Dot/Icm型IVB分泌系统（T4BSS）底物的基因。PtVFX/2014还遗传了一个罕见的约65 kb的致病岛，携带毒力因子和解毒酶，据信这有助于在水库和人巨噬细胞中出现最适合的菌株，以及一个约37.5 kb的物种间转移（来自橡树乳酸菌）基因组岛（包含lvh/lvr T4ASS簇），这在嗜肺乳酸菌物种中从未发现过完整的基因组岛。PtVFX/2014编码了另一个靠近crispr相关基因的lvh/lvr集群，这可能促进嗜肺乳杆菌从环境细菌向人类病原体的转变。总的来说，这种独特的基因组构成可能会影响PtVFX/2014适应不同环境的能力，并最终传播并导致人类疾病。
A first strong evidence of person-to-person transmission of Legionnaires’ Disease (LD) was recently reported. Here, we characterize the genetic backbone of this case-related Legionella pneumophila strain (“PtVFX/2014”), which also caused a large outbreak of LD. PtVFX/2014 is phylogenetically divergent from the most worldwide studied outbreak-associated L. pneumophila subspecies pneumophila serogroup 1 strains. In fact, this strain is also from serogroup 1, but belongs to the L. pneumophila subspecies fraseri. Its genomic mosaic backbone reveals eight horizontally transferred regions encompassing genes, for instance, involved in lipopolysaccharide biosynthesis or encoding virulence-associated Dot/Icm type IVB secretion system (T4BSS) substrates. PtVFX/2014 also inherited a rare ~65 kb pathogenicity island carrying virulence factors and detoxifying enzymes believed to contribute to the emergence of best-fitted strains in water reservoirs and in human macrophages, as well as a inter-species transferred (from L. oakridgensis) ~37.5 kb genomic island (harboring a lvh/lvr T4ASS cluster) that had never been found intact within L. pneumophila species. PtVFX/2014 encodes another lvh/lvr cluster near to CRISPR-associated genes, which may boost L. pneumophila transition from an environmental bacterium to a human pathogen. Overall, this unique genomic make-up may impact PtVFX/2014 ability to adapt to diverse environments, and, ultimately, to be transmitted and cause human disease.