中文摘要：噬菌体疗法重新激起了人们用它治疗细菌感染的兴趣。该应用的主要前提在于定义噬菌体感染细菌的分子靶点。本文研究了易感宿主肺炎克雷伯菌KKBO-1对裂解噬菌体phi BO1E的抗性遗传基础。通过高多重感染获得了KKBO-1的噬菌体抗性突变体，选择其中一个BO-FR-1，进行后续实验，包括用梅隆内拉型凯丹菌感染模型评估毒力及全基因组测序。与亲本菌株相比，噬菌体感染后BO-FR-1的死亡率显著较低。BO-FR-1基因组与KKBO-1的区别在于wbaP基因发生了无义突变，wbaP基因编码一种糖基转移酶，该酶参与了荚膜多糖(CPS)生物合成的第一步。当BO-FR-1与wbaP基因组成互补时，其噬菌体易感性恢复，表明phi BO1E感染KKBO-1针对的是细菌CPS。有趣的是，BO-FR-1的毒力低于亲本菌株，表明在噬菌体、病原菌和宿主相互作用的背景下，噬菌体抗性的出现可能于宿主有利。
外文摘要：Phage therapy is now reconsidered with interest in the treatment of bacterial infections. A major piece of information for this application is the definition of the molecular targets exploited by phages to infect bacteria. Here, the genetic basis of resistance to the lytic phage phi BO1E by its susceptible host Klebsiella pneumoniae KKBO-1 has been investigated. KKBO-1 phage-resistant mutants were obtained by infection at high multiplicity. One mutant, designated BO-FR-1, was selected for subsequent experiments, including virulence assessment in a Galleria mellonella infection model and characterization by whole-genome sequencing. Infection with BO-FR-1 was associated with a significantly lower mortality when compared to that of the parental strain. The BO-FR-1 genome differed from KKBO-1 by a single nonsense mutation into the wbaP gene, which encodes a glycosyltransferase involved in the first step of the biosynthesis of the capsular polysaccharide (CPS). Phage susceptibility was restored when BO-FR-1 was complemented with the constitutive wbaP gene. Our results demonstrated that phi BO1E infects KKBO-1 targeting the bacterial CPS. Interestingly, BO-FR-1 was less virulent than the parental strain, suggesting that in the context of the interplay among phage, bacterial pathogen and host, the emergence of phage resistance may be beneficial for the host.
外文关键词：Klebsiella pneumoniae；Klebsiella pneumoniae carbapenemase KPC；Sequence type 258；phage；Podoviridae；virulence；capsule；polysaccharide；phage resistance mechanism
作者：De Angelis, LH；Poerio, N；Di Pilato, V；De Santis, F；Antonelli, A；Thaller, MC；Fraziano, M；Rossolini, GM；D'Andrea, MM
作者单位：Univ Siena；Univ Roma Tor Vergata；Univ Genoa；Univ Florence；Florence Careggi Univ Hosp
期刊名称：MICROORGANISMS
期刊影响因子：4.152
出版年份：2021
出版刊次：4
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