title: Characterization of specific alleles in InlA and PrfA of Listeria monocytogenes isolated from foods in Osaka, Japan and their ability to invade Caco-2 cells.
abstract: Listeria monocytogenes expresses the surface protein internalin A (InlA), enabling the invasion of human intestinal epithelial cells to cause severe food-borne diseases. Full-length sequence analysis of inlA of 114 food isolates resulted in the detection of 29 isolates with a premature stop codon (PMSC) mutation and 6 isolates with 3-codon deletion mutations (aa 738 to 740) in inlA. The isolates with inlA PMSCs demonstrated a significantly lower level of invasion than the other food isolates in a Caco-2 cell invasion assay (P<0.01), but the isolates with the 3-codon deletion exhibited invasion comparable to the isolates with non-truncated InlA (P>0.05). According to analysis of the positive regulatory factor A (PrfA) sequences of 114 L. monocytogenes isolates, 7 isolates of serotype 1/2a from chicken samples contained a PrfA protein with a 5-nucleotide deletion from 712 to 716, including a stop codon. Although the isolates with a 5-nucleotide deletion in prfA demonstrated invasion comparable to the isolates with non-truncated InlA and PrfA after growth at 30 °C (P>0.05), they exhibited a significantly higher level of invasion than the other isolates after growth at 20 °C (P<0.01). To the authors' knowledge, this is the first report of L. monocytogenes isolates with the stop-codon deletion of PrfA.
authors.affiliation: Department of Infectious Diseases, Osaka Prefectural Institute of Public Health, 1-3-69 Nakamichi, Higashinari-ku, Osaka 537-0025, Japan. Electronic address: kanki@iph.pref.osaka.jp.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kanki
authors.affiliation: Department of Infectious Diseases, Osaka Prefectural Institute of Public Health, 1-3-69 Nakamichi, Higashinari-ku, Osaka 537-0025, Japan.
authors.forename: Hisayo
authors.initials: H
authors.lastname: Naruse
authors.affiliation: Department of Infectious Diseases, Osaka Prefectural Institute of Public Health, 1-3-69 Nakamichi, Higashinari-ku, Osaka 537-0025, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Taguchi
authors.affiliation: Department of Infectious Diseases, Osaka Prefectural Institute of Public Health, 1-3-69 Nakamichi, Higashinari-ku, Osaka 537-0025, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kumeda
mesh_terms: D000483:Alleles; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D018938:Caco-2 Cells; D002417:Cattle; D002645:Chickens; D018389:Codon, Nonsense; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D006801:Humans; D007564:Japan; D008089:Listeria monocytogenes / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D008088:Listeriosis / Q000382:microbiology*; D008460:Meat / Q000382:microbiology*; D009154:Mutation; D010454:Peptide Termination Factors / Q000235:genetics*; D013552:Swine
chemical_list: D001426:Bacterial Proteins; D018389:Codon, Nonsense; D010454:Peptide Termination Factors; C545356:PrfA protein, Listeria monocytogenes; C069761:internalin protein, Bacteria
keywords: Cellular invasion; InlA; Listeria monocytogenes; PMSC; PrfA