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United States Department of Agriculture

Agricultural Research Service

Research Project: VALIDATION OF THE EFFECT OF INTERVENTIONS AND PROCESSES ON PERSISTENCE OF PATHOGENS ON FOODS Title: Reduced virulence of an adenylosuccinate lyase transposon mutant of a serotype 4b strain of Listeria monocytogenes

Authors
item Faith, Nancy -
item Czuprynski, Charles -
item Kim, Jae-Won -
item Kathariou, Sophia -
item Sahaghian, Robert -
item Luchansky, John

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2009
Publication Date: May 5, 2010
Citation: Faith, N.G., Czuprynski, C.J., Kim, J., Kathariou, S., Sahaghian, R., Luchansky, J.B. 2010. Reduced virulence of an adenylosuccinate lyase transposon mutant of a serotype 4b strain of Listeria monocytogenes. [abstract]. International Symposium on Problems of Listeriosis. p.1.

Technical Abstract: A severe outbreak of listeriosis occurred in 1998-99 as a result of contamination of frankfurters with a serotype 4b strain of Listeria monocytogenes. We compared several characteristics of strain H7550, isolated from frankfurters from this outbreak, and a plasmid-free derivative (H7550cds) of this strain lacking the cadmium resistance plasmid pLM80, with that of selected transposon mutant derivatives of both strains. We assessed virulence via intragastric (i.g.) inoculation of anesthetized A/J mice with approximately 10**6 CFU of the individual strains. A transposon mutant of strain H7550 that lacks adenylosuccinate lyase activity (strain J22F), and a non-hemolytic (LLO-) transposon mutant of strain H7550cds (J29H), were avirulent in our mouse model. We did not recover viable cells from the spleen, liver, blood, gallbladder, or ceca of mice inoculated with either strain J22F or J29H, whereas the respective parent strains H7550 and its cadmium sensitive derivative H7550cds were equally virulent for mice. We observed no significant difference in the resistance of stationary phase cells of the plasmid-harboring versus plasmid-free strains to synthetic gastric fluid at pH 4.5. Also, all four strains formed biofilms on plastic surfaces within 24 hr in vitro. Strain J22F was better able to form biofilms in vitro than its parent strain H7550, whereas the LLO-negative mutant strain J29H was not significantly different from its parent strain H7550cds in biofilm formation. These results provide the first evidence that adenylosuccinate lyase activity is required for virulence of L. monocytogenes in mice. These data also demonstrate that LLO is not required for biofilm formation in vitro.

Last Modified: 11/28/2014
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