title: Genetic organization of ascB-dapE internalin cluster serves as a potential marker for Listeria monocytogenes sublineages IIA, IIB, and IIC.
abstract: Listeria monocytogenes is an important foodborne pathogen that comprises four genetic lineages: I, II, III, and IV. Of these, lineage II is frequently recovered from foods and environments and responsible for the increasing incidence of human listeriosis. In this study, the phylogenetic structure of lineage II was determined through sequencing analysis of the ascB-dapE internalin cluster. Fifteen sequence types proposed by multilocus sequence typing based on nine housekeeping genes were grouped into three distinct sublineages, IIA, IIB, and IIC. Organization of the ascBdapE internalin cluster could serve as a molecular marker for these sublineages, with inlGHE, inlGC2DE, and inlC2DE for IIA, IIB, and IIC, respectively. These sublineages displayed specific genetic and phenotypic characteristics. IIA and IIC showed a higher frequency of recombination (rho/theta). However, recombination events had greater effect (r/m) on IIB, leading to its high nucleotide diversity. Moreover, IIA and IIB harbored a wider range of internalin and stress-response genes, and possessed higher nisin tolerance, whereas IIC contained the largest portion of low-virulent strains owing to premature stop codons in inlA. The results of this study indicate that IIA, IIB, and IIC might occupy different ecological niches, and IIB might have a better adaptation to a broad range of environmental niches.
authors.affiliation: Zhejiang University Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 388 Yuhangtang Road, Hangzhou, Zhejiang 310058, P.R. China.
authors.forename: Jianshun
authors.initials: J
authors.lastname: Chen
authors.forename: Chun
authors.initials: C
authors.lastname: Fang
authors.forename: Ningyu
authors.initials: N
authors.lastname: Zhu
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Lv
authors.forename: Changyong
authors.initials: C
authors.lastname: Cheng
authors.forename: Yijiang
authors.initials: Y
authors.lastname: Bei
authors.forename: Tianlun
authors.initials: T
authors.lastname: Zheng
authors.forename: Weihuan
authors.initials: W
authors.lastname: Fang
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D015373:Bacterial Typing Techniques; D006801:Humans; D008089:Listeria monocytogenes / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D008088:Listeriosis / Q000382:microbiology*; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D010802:Phylogeny
chemical_list: D001426:Bacterial Proteins