A New Perspective on Listeria monocytogenes Evolution

PLoS Pathogens

Rachel Lavenir¹  Florian Hollandt¹  Thierry Wirth²  Alban Le Monnier²  Marc Lecuit³  Marie Ragon⁴  Sylvain Brisse⁵ 

[1] Ecole Pratique des Hautes Etudes, Muséum National d'Histoire Naturelle, Department of Systematics and Evolution, Paris, France;Institut Pasteur, Centre National de Référence des Listeria and World Health Organization Collaborating Centre for Foodborne Listeriosis, Paris, France;Institut Pasteur, Genotyping of Pathogens and Public Health Platform (PF8), Paris, France;Institut Pasteur, Laboratoire des Listeria, Paris, France;Institut Pasteur, Microbes and Host Barriers Group, Paris, France

关键词: Listeria monocytogenes;    Evolutionary genetics;    Phylogenetic analysis;    Cloning;    Animal phylogenetics;    Mutation;    Phylogenetics;    Virulence factors;   

DOI  :  10.1371/journal.ppat.1000146

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Listeria monocytogenes is a model organism for cellular microbiology and host–pathogen interaction studies and an important food-borne pathogen widespread in the environment, thus representing an attractive model to study the evolution of virulence. The phylogenetic structure of L. monocytogenes was determined by sequencing internal portions of seven housekeeping genes (3,288 nucleotides) in 360 representative isolates. Fifty-eight of the 126 disclosed sequence types were grouped into seven well-demarcated clonal complexes (clones) that comprised almost 75% of clinical isolates. Each clone had a unique or dominant serotype (4b for clones 1, 2 and 4, 1/2b for clones 3 and 5, 1/2a for clone 7, and 1/2c for clone 9), with no association of clones with clinical forms of human listeriosis. Homologous recombination was extremely limited (r/m<1 for nucleotides), implying long-term genetic stability of multilocus genotypes over time. Bayesian analysis based on 438 SNPs recovered the three previously defined lineages, plus one unclassified isolate of mixed ancestry. The phylogenetic distribution of serotypes indicated that serotype 4b evolved once from 1/2b, the likely ancestral serotype of lineage I. Serotype 1/2c derived once from 1/2a, with reference strain EGDe (1/2a) likely representing an intermediate evolutionary state. In contrast to housekeeping genes, the virulence factor internalin (InlA) evolved by localized recombination resulting in a mosaic pattern, with convergent evolution indicative of natural selection towards a truncation of InlA protein. This work provides a reference evolutionary framework for future studies on L. monocytogenes epidemiology, ecology, and virulence.

【 授权许可】

CC BY