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 (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.

Characterization of antibiogram fingerprints in Listeria monocytogenes recovered from irrigation water and agricultural soil samples

“…The prevalence of the hylA and plcB genes in the present study was 100%. The hylA and plcB mediate the release of the bacterial cells into the cytoplasm of the host and promotes the escape of the bacteria from bound vacuoles and the surface protein actin A respectively [8]. This rate is in tune with the prevalence rate observed in the study of [3].…”

Prevalence, Genotypic Characteristics and Antibiotic Resistance of Listeria monocytogenes From Retail Foods in Bulk in Zhejiang Province, China

“…Four Listeria pathogenicity islands (LIPI) have been verified thus far, which are involved in invasion, survival and colonization of L. monocytogenes in host tissues. LIPI-1 contains six genes including hly , prfA , plcA , plcB , mpl , and actA (Hamon and Cossart, 2011; Travier and Lecuit, 2014; Mitchell et al, 2015; Rupp et al, 2015; Wang et al, 2017a; Hadjilouka et al, 2018; Poimenidou et al, 2018). LIPI-2 encodes a series of internalin family proteins which interact with the molecular cell surface and are essential for host cell adherence and virulence (McGann et al, 2007).…”

Characteristics of Listeria Monocytogenes Strains Persisting in a Meat Processing Facility over a 4-Year Period

“…Different strains of L. monocytogenes also exhibited high MBCs for PAA in the range of up to 0.5% [28,29,30,31]. In contrast, others concluded that PAA was able to significantly reduce L. monocytogenes from multispecies biofilms at 0.15% [32] and 0.3% [30], respectively.…”