Virulence of different strains ofListeria monocytogenes serovar 1/2a

“…However, treatment of these mutants with partially purified p60 from wild-type L. monocytogenes restores their invasiveness (3,25). One rough strain, L. monocytogenes RIII (SLCC 5779) (19), forms particularly long cell chains which disaggregate when they are exposed to purified p60 or ultrasonicated (25). Although this strain has no mutation in the gene encoding p60 (initially termed iap for invasion-associated protein), it produces greatly reduced amounts of p60, whereas iap-specific mRNA is present at the same level as in the wildtype strain (23).…”

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confidence: 99%

Deletion of the Gene Encoding p60 inListeria monocytogenesLeads to Abnormal Cell Division and Loss of Actin-Based Motility

et al. 2003

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Protein p60 encoded by the iap gene is regarded as an essential gene product of Listeria monocytogenes. Here we report, however, the successful construction of a viable iap deletion mutant of L. monocytogenes EGD. The mutant, which produces no p60, shows abnormal septum formation and tends to form short filaments and hooked forms during logarithmic growth. These abnormal bacterial cells break into almost normal sized single bacteria in the late-stationary-growth phase. The iap mutant is strongly attenuated in a mouse model after intravenous injection, demonstrating the importance of p60 during infection, and the invasiveness of the ⌬iap mutant for 3T6 fibroblasts and Caco-2 epithelial cells is slightly reduced. Upon uptake by epithelial cells and macrophages, the iap mutant escapes from the phagosome into the cytosol with the same efficiency as the wild-type strain, and the mutant bacteria also grow intracellularly at a rate similar to that of the wild-type strain. Intracellular movement and cell-to-cell spread are drastically reduced in various cell lines, since the iap-negative bacteria fail to induce the formation of actin tails. However, the bacteria are covered with actin filaments. Most intracellular bacteria show a nonpolar and uneven distribution of ActA around the cell, in contrast to that for the wild-type strain, where ActA is concentrated at the old pole. In an iap ؉ revertant strain that produces wild-type levels of p60, intracellular movement, cell-to-cell spread, and polar distribution of ActA are fully restored. In vitro analysis of ActA distribution on the filaments of the ⌬iap strain shows that the loss of bacterial septum formation leads to ActA accumulation at the presumed division sites. In the light of data presented here and elswhere, we propose to rename iap (invasion-associated protein) cwhA (cell wall hydrolase A).

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“…In the experimental mouse model system [10] the slightly hemolytic L. monocytogenes strains are quite virulent, whereas the extremely hemolytic L. ivanovii (formerly L. monocytogenes SvS or L bulgarica) [11 ], is only moderately virulent. …”

Section: Introductionmentioning

confidence: 99%

Production, purification and characterization of hemolysins from Listeria ivanovii and Listeria monocytogenes Sv4b

Kreft

1989

FEMS Microbiology Letters

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SUMMARYIn culture supematants of both Listeria ivanovii and Listeria monocytogenes Sv4b, for the first time a hemolysin of molecular weight 58 kDa was identified, which had all the characteristics of an SH-activated cytolysin, and which was therefore identified as Iisteriolysin 0 (LLO). In the case of L. ivanovii a second major supematant protein of molecular weight 24 kDa co-purified with LLO. However, the function of this protein has to be determined. In culture supematants of L. ivanovii a sphingomyelinase and a Iecithinase activity could be detected, both enzymatic activities together contributing to the pronounced hemolysis caused by L. ivanovii. The N-tenninal amino acid sequences of LLO and the 24 kDa from L. ivanovii are shown.

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Virulence of different strains ofListeria monocytogenes serovar 1/2a

Cited by 70 publications

References 30 publications

Hemolysin from listeria — Biochemistry, genetics and function in pathogenesis

Hemolysin from listeria — Biochemistry, genetics and function in pathogenesis

Deletion of the Gene Encoding p60 inListeria monocytogenesLeads to Abnormal Cell Division and Loss of Actin-Based Motility

Production, purification and characterization of hemolysins from Listeria ivanovii and Listeria monocytogenes Sv4b

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