Characterization of virulent and avirulent Listeria monocytogenes strains by PCR amplification of putative transcriptional regulator and internalin genes.
Listeria monocytogenes is an opportunistic bacterial pathogen that is an important cause of human food-borne illness worldwide. However, L. monocytogenes strains demonstrate considerable variation in pathogenic potential. In this report, virulent and avirulent L. monocytogenes isolates were compared by using a comparative screening strategy. Two clones were identified that contained DNA that was only present in virulent L. monocytogenes strains. PCR primers were designed for three genes from these clones and for five other selected L. monocytogenes genes. All eight primer sets predominantly detected virulent L. monocytogenes isolates, as determined by a mouse virulence assay; one of the putative internalin genes, lmo2821, was detected in all strains that were considered to be virulent. Primers from these eight genes were then tested by PCR against a larger panel of bacterial strains; each of the genes was detected predominantly in clinical or food L. monocytogenes isolates, rather than environmental isolates. The findings from this study suggest that virulent L. monocytogenes strains may possess genes that are not present in avirulent isolates, which could serve as markers for PCR assessment of L. monocytogenes virulence.
Liu
Dongyou
D
Department of Basic Sciences1 and Department of Pathobiology and Population Medicine2, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, 39762-6100, USA.
Ainsworth
A Jerald
AJ
Department of Basic Sciences1 and Department of Pathobiology and Population Medicine2, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, 39762-6100, USA.
Austin
Frank W
FW
Department of Basic Sciences1 and Department of Pathobiology and Population Medicine2, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, 39762-6100, USA.
Lawrence
Mark L
ML
Department of Basic Sciences1 and Department of Pathobiology and Population Medicine2, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, 39762-6100, USA.
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D005260:Female; D005809:Genes, Regulator; D008089:Listeria monocytogenes / Q000235:genetics* / Q000472:pathogenicity; D051379:Mice; D016133:Polymerase Chain Reaction / Q000379:methods*; D014774:Virulence
D001426:Bacterial Proteins; C069761:internalin protein, Bacteria