Evolutionary history of the genus Listeria and its virulence genes (original) (raw)
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Research in Microbiology, 1989
Various parts of the hlyA gene region of Listeria monocytogenes which encodes a major virulence factor, listeriolysin O, have been used to detect the presence of homologous sequences in other species of the genus Listeria. Under low-stringency hybridization conditions, sequences homologous to the hlyA gene and its 5' adjacent regions were detected in the haemolytic and pathogenic species L. ivanovii, and in the haemolytic but non-pathogenic species L. seeligeri. In contrast, the region located downstream from hlyA appeared specific to L. monocytogenes. None of the probes spanning the region revealed homologies between L. monocytogenes and the non-pathogenic and non-haemolytic members of the genus, L. innocua, L. murrayi and L. welshimeri. Among various strains of L. monocytogenes tested, the gene hlyA and its 3' adjacent region appeared well-conserved. In contrast, a restriction length polymorphism was detected in the region located upstream from hlyA with no obvious correlation with the haemolytic phenotype or the serovar of the strains tested.
Infection and Immunity, 2001
Most major food-borne outbreaks of listeriosis in Europe and in the United States have been caused by genetically closely related Listeria monocytogenes strains of serotype 4b. In order to assess whether genomic loci exist that could underlie this increased epidemic potential, we subtracted the genome of the virulent prototype L. monocytogenes strain EGD from a prototype epidemic strain. A total of 39 DNA fragments corresponding to 20% of an estimated total of 150 to 190 kb of differential genome material were isolated. For 21 of these fragments, no function on the basis of homology could be predicted. Of the remaining 18 fragments, 15 had homologies to bacterial surface proteins, some of which have been implicated in virulence mechanisms such as cell invasion, adhesion, or immune escape. Southern hybridization of arrays containing the epidemic-clonespecific DNA segments with genomic DNA of different L. monocytogenes strains was consistent with the current lineage division. Surprisingly, however, some of the fragments hybridized in a mosaic-like fashion to genomes of two other Listeria species, the animal pathogen L. ivanovii and the nonpathogen L. innocua. Taken together, our results provide a starting point for the identification of epidemic-trait-associated genes.
Infection and Immunity, 2001
Most major food-borne outbreaks of listeriosis in Europe and in the United States have been caused by genetically closely related Listeria monocytogenes strains of serotype 4b. In order to assess whether genomic loci exist that could underlie this increased epidemic potential, we subtracted the genome of the virulent prototype L. monocytogenes strain EGD from a prototype epidemic strain. A total of 39 DNA fragments corresponding to 20% of an estimated total of 150 to 190 kb of differential genome material were isolated. For 21 of these fragments, no function on the basis of homology could be predicted. Of the remaining 18 fragments, 15 had homologies to bacterial surface proteins, some of which have been implicated in virulence mechanisms such as cell invasion, adhesion, or immune escape. Southern hybridization of arrays containing the epidemic-clone-specific DNA segments with genomic DNA of different L. monocytogenes strains was consistent with the current lineage division. Surpris...
Pathogenicity islands and virulence evolution in Listeria
Microbes and Infection, 2001
As in other bacterial pathogens, the virulence determinants of Listeria species are clustered in genomic islands scattered along the chromosome. This review summarizes current knowledge about the structure, distribution and role in pathogenesis of Listeria virulence loci. Hypotheses about the mode of acquisition and evolution of these loci in this group of Gram-positive bacteria are presented and discussed. © 2001 Éditions scientifiques et médicales Elsevier SAS Listeria / Listeria monocytogenes / Listeria innocua / Listeria ivanovii / pathogenicity islands / LIPI-1 / LIPI-2 / LRR proteins / virulence evolution / microbial pathogenesis *Correspondence and reprints. E-mail address: vazquez@eucmax.sim.ucm.es (J.A. Vázquez-Boland).
Infection and immunity, 1997
A total of 133 Listeria monocytogenes isolates were characterized by ribotyping and allelic analysis of the virulence genes hly, actA, and inlA to uncover linkages between independent phylogenetic and specific virulence markers. PCR-restriction fragment length polymorphisms revealed 8 hly, 11 inl4, and 2 actA alleles. The combination of these virulence gene alleles and ribotype patterns separated L. monocytogenes into three distinct lineages. While distinct hly and inlA alleles were generally found to cluster into these three lineages, actA alleles segregated independently. These three phylogenetic lineages were confirmed when 22 partial actA DNA sequences were analyzed. The clinical history of the L. monocytogenes strains showed evidence for differences in pathogenic potential among the three lineages. Lineage I contains all strains isolated during epidemic outbreaks of listeriosis, while no human isolates were found in lineage III. Animal isolates were found in all three lineages....
Genomics Data, 2014
More than 98% of reported human listeriosis cases are caused by specific serotypes within genetic lineages I and II. The genome sequence of Listeria monocytogenes lineage III strain HCC23 (serotype 4a) enables whole genomic comparisons across all three L. monocytogenes lineages. Protein cluster analysis indicated that strain HCC23 has the most unique protein pairs with nonpathogenic species Listeria innocua. Orthology analysis of the genome sequences of representative strains from the three L. monocytogenes genetic lineages and L. innocua (CLIP11262) identified 319 proteins unique to nonpathogenic strains HCC23 and CLIP11262 and 58 proteins unique to pathogenic strains F2365 and EGD-e. BLAST comparison of these proteins with all the sequenced L. monocytogenes and L. innocua revealed 126 proteins unique to serotype 4a and/or L. innocua; 14 proteins were only found in pathogenic serotypes. Some of the 58 proteins unique to pathogenic strains F2365 and EGD-e were previously published and are already known to contribute to listerial virulence.