title: A comparison of selected methods for measuring the virulence properties of Listeria spp.
abstract: The comparative ability of different methods to assess virulence of Listeria species was investigated in ten Listeria strains. All strains were initially subjected to pulsed-field gel electrophoresis analysis to determine their relatedness. Virulence characteristics were subsequently tested for by (i) determining the presence of six virulence genes by polymerase chain reaction; (ii) testing for the production of listeriolysin O, phosphatidylcholine phospholipase C, and phosphatidylinositol-specific phospholipase C; (iii) investigating the hydrophobicity of the strains; (iv) determining the strains ability to attach to, enter, and replicate within the Caco-2 cells. Variations in most of the virulence characteristics were obvious across the strains for the range of tests performed. A wide range of anomalous results among methods were apparent. In particular, the presence of virulence genes was found to be unrelated to the production of virulence-associated proteins in vitro, while virulence protein production and hydrophobicity in Listeria monocytogenes were found to be unrelated or marginally related, respectively, to the ability to invade the Caco-2 cell line. It was concluded that the methods investigated were unable to consistently and unequivocally measure the differences in the virulence properties of the strains.
authors.affiliation: Food Science Australia, P.O.Box 3312, Tingalpa DC, Australia. sally.chiu@foodscience.afisc.csiro.au
authors.forename: Sally
authors.initials: S
authors.lastname: Chiu
authors.forename: Paul B
authors.initials: PB
authors.lastname: Vanderlinde
authors.forename: Gary A
authors.initials: GA
authors.lastname: Dykes
mesh_terms: D001422:Bacterial Adhesion / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D018938:Caco-2 Cells; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D006801:Humans; D008087:Listeria / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D008089:Listeria monocytogenes / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D010738:Type C Phospholipases / Q000235:genetics / Q000378:metabolism; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D037521:Virulence Factors; D010738:Type C Phospholipases