Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: UMBRELLA PROJECT FOR FOOD SAFETY

Location: Warmwater Aquaculture Research Unit

Title: Toward an Improved Laboratory Definition of Listeria monocytogenes Virulence

Authors
item Liu, D - MISS. STATE UNIVERSITY
item Lawrence, M - MISS. STATE UNIVERSITY
item Ainsworth, A - MISS. STATE UNIVERSITY
item Austin, F - MISS. STATE UNIVERSITY

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 7, 2007
Publication Date: September 15, 2007
Citation: Liu, D., Lawrence, M.L., Ainsworth, A.J., Austin, F.W. 2007. Toward an Improved Laboratory Definition of Listeria monocytogenes Virulence. International Journal of Food Microbiology. 118(2):101-15.

Interpretive Summary: Listeria monocytogenes is an opportunistic foodborne pathogen that encompasses a diversity of strains with varied virulence. The ability to rapidly determine the pathogenic potential of L. monocytogenes strains is integral to the control and prevention campaign against listeriosis. Early methods for assessing L. monocytogenes virulence include in vivo bioassays and in vitro cell assays. While in vivo bioassays provide a measurement of all virulence determinants of L. monocytogenes, they are not applied routinely due to the requirement for and cost of experimental animals. In vitro cell assays are useful for estimating the virulence of L. monocytogenes strains, but are often slow and sometimes give inconsistent results. Recent identification of novel virulence-specific genes (particularly internalin gene inlJ) has opened a new avenue for rapid, sensitive, and precise differentiation of virulent L. monocytogenes strains from avirulent strains via PCR based assays. The application of DNA sequencing also offers an additional tool for assessing L. monocytogenes virulence potential. Future research needs that may help achieve an improved laboratory definition of L. monocytogenes virulence are reviewed.

Technical Abstract: Listeria monocytogenes is an opportunistic foodborne pathogen that encompasses a diversity of strains with varied virulence. The ability to rapidly determine the pathogenic potential of L. monocytogenes strains is integral to the control and prevention campaign against listeriosis. Early methods for assessing L. monocytogenes virulence include in vivo bioassays and in vitro cell assays. While in vivo bioassays provide a measurement of all virulence determinants of L. monocytogenes, they are not applied routinely due to their reliance on experimental animals whose costs have become increasingly prohibitive. As a low cost alternative, in vitro cell assays are useful for estimating the virulence of L. monocytogenes strains. However, these assays are often slow, and at times variable. Prior attempts to ascertain L. monocytogenes virulence by targeting virulence-associated proteins and genes have been largely unsuccessful, since many of the assay targets are present in both virulent and avirulent strains. Recent identification of novel virulence-specific genes (particularly internalin gene inlJ) has opened a new avenue for rapid, sensitive, and precise differentiation of virulent L. monocytogenes strains from avirulent strains. The application of DNA sequencing technique also offers an additional tool for assessing L. monocytogenes virulence potential. By providing an update on the laboratory methods that have been reported for the determination of L. monocytogenes pathogenicity, this review discusses future research needs that may help achieve an improved laboratory definition of L. monocytogenes virulence.

Last Modified: 8/30/2014