title: Evaluation of transcription levels of inlA, inlB, hly, bsh and prfA genes in Listeria monocytogenes strains using quantitative reverse-transcription PCR and ability of invasion into human CaCo-2 cells.
abstract: Listeria monocytogenes virulence depends on the activity of well-characterized virulence factors. In this study, transcription levels of inlA, inlB, hly, bsh and prfA genes in L. monocytogenes strains, and the ability of invasion into CaCo-2 cells were investigated. Serotyping, multiplex-PCR for serovar identification and restriction fragment analysis of inlA were performed. Transcription levels and invasiveness were evaluated by quantitative reverse-transcription PCR and by in vitro assays, respectively. The isolates were of serovars 1/2a, 4b, 1/2c, 1/2b and 3a. Full-length inlA profiles were found for nine of ten clinical isolates, while five of seven cultures from foods showed truncated profile. The analysis of transcription levels of virulence factors encoding genes demonstrated a substantial inter-strain heterogeneity, with clinical strains showing higher levels for almost all genes than isolates from food. A correlation between transcription levels of inlA and inlB, as well as between bsh and prfA, was observed. Significant differences between clinical strains and food isolates in the invasion of CaCo-2 cells were found. Analysis of gene transcription and invasiveness of human cells suggests different virulence phenotypes among L. monocytogenes populations, and this characterization could be a useful tool for risk assessment purposes and for the development of public health strategies.
authors: Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy.
authors: Manuela
authors: M
authors: Tamburro
authors: Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy sammarco@unimol.it.
authors: Michela Lucia
authors: ML
authors: Sammarco
authors: Department of Technology and Health, Istituto Superiore di Sanità, Rome, Italy.
authors: Maria Grazia
authors: MG
authors: Ammendolia
authors: Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy.
authors: Incoronata
authors: I
authors: Fanelli
authors: European Reference Laboratory for Escherichia coli, Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy.
authors: Fabio
authors: F
authors: Minelli
authors: Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy.
authors: Giancarlo
authors: G
authors: Ripabelli
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics; D018938:Caco-2 Cells; D005516:Food Microbiology; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics; D006460:Hemolysin Proteins / Q000235:genetics; D006801:Humans; D008089:Listeria monocytogenes / Q000235:genetics* / Q000472:pathogenicity*; D008565:Membrane Proteins / Q000235:genetics; D010454:Peptide Termination Factors / Q000235:genetics; D010641:Phenotype; D012150:Polymorphism, Restriction Fragment Length; D060888:Real-Time Polymerase Chain Reaction; D065288:Serogroup; D012703:Serotyping; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D008565:Membrane Proteins; D010454:Peptide Termination Factors; C545356:PrfA protein, Listeria monocytogenes; C095768:inlB protein, Listeria monocytogenes; C069761:internalin protein, Bacteria; C038705:hlyA protein, Listeria monocytogenes
keywords: Listeria monocytogenes; bsh; cell invasion; hly; inlA; inlB; prfA; qRT-PCR; virulence factors