Data_Sheet_1_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.XLSX

<p>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 (π) 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 π 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.</p

Image_1_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.PDF

<p>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 (π) 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 π 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.</p

Transmission electron micrographs of <i>E</i>. <i>coli</i> phages ɸAPCEc01 (a), ɸAPCEc02 (b), and ɸAPCEc03 (c).

<p>The thin arrows in micrograph c indicate the 3 flexible fibres attached to the distal end of the phage tail. The terminal baseplate spike in c is illustrated by the thick arrow.</p

Strains used in this study and host range of phages ɸAPCEc01, ɸAPCEc02 and ɸAPCEc03.

<p>Strains used in this study and host range of phages ɸAPCEc01, ɸAPCEc02 and ɸAPCEc03.</p

Effect of a combination of ciprofloxacin HCl and phages ɸAPCEc01, ɸAPCEc02, and ɸAPCEc03, alone or in cocktail, on the growth of <i>E</i>. <i>coli</i> strain DPC6051.

<p>Each condition was tested in triplicate. Bacterial counts were performed after 24 h of incubation, with a detection threshold of 20 cfu/ml. *** p<0.001, ** p<0.01, * p<0.05.</p

Dimensions of the three <i>E</i>. <i>coli</i> phages isolated in this study.

<p>Dimensions of the three <i>E</i>. <i>coli</i> phages isolated in this study.</p

BLAST Ring Image Generator representation of phage ɸAPCEc01 (a), ɸAPCEc02 (b), and ɸAPCEc03 (c) genomes.

<p>The innermost rings show the GC content (black) and GC skew (purple: GC skew[-]; green: GC skew[+]). For each comparison using BRIG, the longest phage genome was used as a reference, and its name is indicated in the middle of the rings. The circles represent the genomes of the phages compared to this reference including the phages described in this study.</p

Genome features of phages ɸAPCEc01, ɸAPCEc02 and ɸAPCEc03.

<p>Genome features of phages ɸAPCEc01, ɸAPCEc02 and ɸAPCEc03.</p

Effect of single phages ɸAPCEc01 (a), ɸAPCEc02 (b), ɸAPCEc03 (c), and a three-phage cocktail (d) on a 24 h-biofilm formed by <i>E</i>. <i>coli</i> strain DPC6051, after 24 h (■) and 48 h () of contact between phage and biofilm.

<p>Biofilm activity was assessed by OD_492nm measures after treatment with XTT supplemented with menadione. ***p<0.001; **p<0.01; *p<0.05.</p

Bacterial challenge test.

<p>The optical density (OD_600nm) was measured after 24 h of contact between <i>E</i>. <i>coli</i> strain DPC6051 and phage ɸAPCEc01 (a), phage ɸAPCEc02 (b), phage ɸAPCEc03 (c), and a cocktail of the three phages (d). *** p<0.001, * p<0.05.</p