PDF(Pubmed)
Abstract：
Legionella is a common intracellular parasitic bacterium that infects humans via the respiratory tract, causing Legionnaires\' disease, with fever and pneumonia as the main symptoms. The emergence of highly virulent and azithromycin-resistant Legionella pneumophila is a major challenge in clinical anti-infective therapy. The CRISPR-Cas acquired immune system provides immune defense against foreign nucleic acids and regulates strain biological functions. However, the distribution of the CRISPR-Cas system in Legionella and how it regulates gene expression in L. pneumophila remain unclear. Herein, we assessed 915 Legionella whole-genome sequences to determine the distribution characteristics of the CRISPR-Cas system and constructed gene deletion mutants to explore the regulation of the system based on growth ability in vitro, antibiotic sensitivity, and intracellular proliferation of L. pneumophila. The CRISPR-Cas system in Legionella was predominantly Type II-B and was mainly concentrated in the genome of L. pneumophila ST1 strains. The Type II-B CRISPR-Cas system showed no effect on the strain\'s growth ability in vitro but significantly reduced resistance to azithromycin and decreased proliferation ability due to regulation of the lpeAB efflux pump and the Dot/Icm type IV secretion system. Thus, the Type II-B CRISPR-Cas system plays a crucial role in regulating the virulence of L. pneumophila. This expands our understanding of drug resistance and pathogenicity in Legionella, provides a scientific basis for the prevention of Legionnaires\' disease outbreaks and the rational use of clinical drugs, and facilitates effective treatment of Legionnaires\' disease.
摘要：
军团菌是一种常见的细胞内寄生菌，通过呼吸道感染人类，导致军团病,以发烧和肺炎为主要症状。高毒力和阿奇霉素耐药的嗜肺军团菌的出现是临床抗感染治疗的主要挑战。CRISPR-Cas获得性免疫系统提供针对外源核酸的免疫防御并调节菌株生物学功能。然而,目前尚不清楚CRISPR-Cas系统在军团菌中的分布及其如何调节嗜肺乳杆菌中的基因表达。在这里，我们评估了915个军团菌全基因组序列，以确定CRISPR-Cas系统的分布特征，并构建了基因缺失突变体，以探索基于体外生长能力的系统调控，抗生素敏感性,和嗜肺乳杆菌的细胞内增殖。军团菌的CRISPR-Cas系统主要是II-B型，主要集中在嗜肺乳杆菌ST1菌株的基因组中。II-B型CRISPR-Cas系统对菌株的体外生长能力没有影响，但由于lpeAB外排泵和Dot/IcmIV型分泌系统的调节，对阿奇霉素的抗性和增殖能力显著降低。因此，II-B型CRISPR-Cas系统在调节嗜肺乳杆菌的毒力中起着至关重要的作用。这扩大了我们对军团菌耐药性和致病性的理解，为预防军团病暴发和临床合理用药提供科学依据,并促进军团病的有效治疗。
