A Listeria monocytogenes strain is still virulent despite nonfunctional major virulence genes.
The low-virulence Listeria monocytogenes strains have been previously assigned to 4 phenotypic groups. This study aimed to characterize the A23 strain, which exhibits a pulsed-field gel electrophoresis profile specific to low-virulence strains. This strain has the same causal mutations as the group III strains and a supplementary mutation in the mpl gene, leading to the absence of internalin A expression and the presence of inactive internalin B, phosphatidyl-inositol phospholipase C, and phosphatidylcholine phospholipase C. Despite these mutations in major virulence genes, the A23 strain formed plaques in cell monolayers and contaminated 100% of inoculated mice, suggesting that it evolved from group III strains by acquiring new virulence genes.
Roche
S M
SM
Institut National de la Recherche Agronomique, UR 1282 Infectiologie Animale et Santé Publique, and IFR 136, Agents transmissibles et Infectiologie, Nouzilly, France. sylvie.roche@tours.inra.fr
Grépinet
O
O
Corde
Y
Y
Teixeira
A P
AP
Kerouanton
A
A
Témoin
S
S
Mereghetti
L
L
Brisabois
A
A
Velge
P
P
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D002460:Cell Line; D017353:Gene Deletion; D006801:Humans; D008089:Listeria monocytogenes / Q000472:pathogenicity*; D008088:Listeriosis / Q000382:microbiology; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D054801:Phosphoinositide Phospholipase C / Q000235:genetics; D010738:Type C Phospholipases / Q000235:genetics; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
D001426:Bacterial Proteins; D008565:Membrane Proteins; D037521:Virulence Factors; C095768:inlB protein, Listeria monocytogenes; C069761:internalin protein, Bacteria; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; C105598:phosphatidylcholine-specific phospholipase C