Dataset Information

Virulence Gene Sequencing Highlights Similarities and Differences in Sequences in Listeria monocytogenes Serotype 1/2a and 4b Strains of Clinical and Food Origin From 3 Different Geographic Locations.

ABSTRACT: The prfA-virulence gene cluster (pVGC) is the main pathogenicity island in Listeria monocytogenes, comprising the prfA, plcA, hly, mpl, actA, and plcB genes. In this study, the pVGC of 36 L. monocytogenes isolates with respect to different serotypes (1/2a or 4b), geographical origin (Australia, Greece or Ireland) and isolation source (food-associated or clinical) was characterized. The most conserved genes were prfA and hly, with the lowest nucleotide diversity (?) among all genes (P < 0.05), and the lowest number of alleles, substitutions and non-synonymous substitutions for prfA. Conversely, the most diverse gene was actA, which presented the highest number of alleles (n = 20) and showed the highest nucleotide diversity. Grouping by serotype had a significantly lower ? value (P < 0.0001) compared to isolation source or geographical origin, suggesting a distinct and well-defined unit compared to other groupings. Among all tested genes, only hly and mpl were those with lower nucleotide diversity in 1/2a serotype than 4b serotype, reflecting a high within-1/2a serotype divergence compared to 4b serotype. Geographical divergence was noted with respect to the hly gene, where serotype 4b Irish strains were distinct from Greek and Australian strains. Australian strains showed less diversity in plcB and mpl relative to Irish or Greek strains. Notable differences regarding sequence mutations were identified between food-associated and clinical isolates in prfA, actA, and plcB sequences. Overall, these results indicate that virulence genes follow different evolutionary pathways, which are affected by a strain's origin and serotype and may influence virulence and/or epidemiological dominance of certain subgroups.

SUBMITTER: Poimenidou SV

PROVIDER: S-EPMC5996115 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Publications

Virulence Gene Sequencing Highlights Similarities and Differences in Sequences in Listeria monocytogenes Serotype 1/2a and 4b Strains of Clinical and Food Origin From 3 Different Geographic Locations.

Poimenidou Sofia V SV Dalmasso Marion M Papadimitriou Konstantinos K Fox Edward M EM Skandamis Panagiotis N PN Jordan Kieran K

Frontiers in microbiology 20180605

The prfA-virulence gene cluster (pVGC) is the main pathogenicity island in Listeria monocytogenes, comprising the prfA, plcA, hly, mpl, actA, and plcB genes. In this study, the pVGC of 36 L. monocytogenes isolates with respect to different serotypes (1/2a or 4b), geographical origin (Australia, Greece or Ireland) and isolation source (food-associated or clinical) was characterized. The most conserved genes were prfA and hly, with the ...[more]

PMID: 29922249

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Project description:Recently, we have identified a link between four listeriosis incidents/outbreaks to a variant of Listeria monocytogenes (Lm) serotype 4b strains, 4bV. Although 4bV strains have been reported from clinical specimens as well as from foods, listeriosis outbreaks occurring in 2014-2016 were the first reported outbreaks involving 4bV in the USA. Since traditional typing methods do not detect members of this group, we undertook a systematic and retrospective analysis of all Lm in the NCBI WGS Sequence Read Archive database to investigate the burden of 4bV strains among all listeriosis cases. This analysis identified the presence of isolates causing sporadic cases as well as those associated with the aforementioned outbreaks, as determined by WGS and traditional epidemiology. In total, approximately 350 Lm 4bV strains were identified from multiple parts of the USA as well as from Australia and Chile, dating back to 2001. The genomic relatedness of these strains was compared using the CFSAN SNP Pipeline and multi-virulence-locus sequence typing (MVLST). Using the CFSAN Pipeline tool, the 4bV strains were found to group into seven clusters that were separate from 4b strains. All seven clades appeared to contain isolates from both clinical and non-clinical sources. Conversely, the MVLST analysis revealed that practically all of the strains belonged to a single clade, suggesting that 4bV strains from disparate geographic regions and sources are under varied selective pressure, restricting diversity across these six virulence loci while allowing more variability across the genome as a whole. Further evaluation of these 4bV strains identified genes potentially acquired from a lineage II source external to the lmo0733-lmo0739 region, as well as highly conserved SNPs unique to the 4bV strains when compared to those from other lineages. Taken together, these data suggest that 4bV strains have undergone adaptive responses to selective pressures that may enhance survival in the environment while maintaining the pathogenic potential of serotype 4b strains.

Dataset Information

Virulence Gene Sequencing Highlights Similarities and Differences in Sequences in Listeria monocytogenes Serotype 1/2a and 4b Strains of Clinical and Food Origin From 3 Different Geographic Locations.

Publications

Virulence Gene Sequencing Highlights Similarities and Differences in Sequences in <i>Listeria monocytogenes</i> Serotype 1/2a and 4b Strains of Clinical and Food Origin From 3 Different Geographic Locations.

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