A molecular marker for evaluating the pathogenic potential of foodborne Listeria monocytogenes

J Infect Dis. 2004 Jun 1;189(11):2094-100. doi: 10.1086/420853. Epub 2004 May 14.


Background: Internalin mediates entry of Listeria monocytogenes into some human cultured cell lines and crossing of the intestinal barrier in transgenic mice expressing its receptor, human E-cadherin, in enterocytes. The relevance of these findings for humans is challenged by the observation that some L. monocytogenes isolates express a truncated nonfunctional form of internalin.

Methods: We investigated expression of internalin by use of immunoblot assay in 300 clinical strains obtained in France in a single year and a representative set of 150 strains obtained from food products during the same period.

Results: Clinical strains expressed full-length internalin far more frequently (288/300 strains [96%]) than did strains recovered from food products (98/150 strains [65%]; odds ratio, 12.73; 95% confidence interval, 6.27-26.34; P<1 x 10(-7)). All 61 strains (100%) from pregnancy-related cases, 55 (98%) of 56 strains from patients with central nervous system infections, and 151 (93%) of 162 strains from patients with bacteremia expressed full-length internalin. All 110 strains belonging to serovar 4b, the most frequently implicated serovar in human listeriosis, expressed full-length internalin.

Conclusions: This study demonstrates the critical role of internalin in the pathogenesis of human listeriosis. It provides a molecular explanation for the predominance of serovar 4b among clinical strains and supports the usefulness of studying the expression of internalin as a marker of virulence in humans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteremia / microbiology
  • Bacterial Proteins / biosynthesis*
  • Bacterial Proteins / metabolism
  • Biomarkers
  • Central Nervous System Infections / microbiology
  • Female
  • Food Microbiology
  • Humans
  • Immunoblotting
  • Listeria monocytogenes / metabolism*
  • Listeria monocytogenes / pathogenicity*
  • Listeriosis / microbiology*
  • Pregnancy
  • Virulence


  • Bacterial Proteins
  • Biomarkers
  • internalin H protein, Listeria monocytogenes