A New Perspective on Listeria monocytogenes Evolution

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