Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine

Hangzhou, China

Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine

Hangzhou, China
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Zhao H.,Zhejiang University | Zhao H.,Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine | Chen J.,Zhejiang University | Chen J.,Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine | And 10 more authors.
Journal of Microbiology | Year: 2011

Listeria monocytogenes is a foodborne pathogen of humans and animals. The majority of human listeriosis cases are caused by strains of lineages I and II, while lineage III strains are rare and seldom implicated in human listeriosis. We revealed by 16S rRNA sequencing the special evolutionary status of L. monocytogenes lineage III, which falls between lineages I and II strains of L. monocytogenes and the non-pathogenic species L. innocua and L. marthii in the dendrogram. Thirteen lineage III strains were then characterized by polyphasic approaches. Biochemical reactions demonstrated 8 biotypes, internalin profiling identified 10 internal-in types clustered in 4 groups, and multilocus sequence typing differentiated 12 sequence types. These typing schemes show that lineage III strains represent the most diverse population of L. monocytogenes, and comprise at least four subpopulations IIIA-1, IIIA-2, HIB, and IIIC. The in vitro and in vivo virulence assessments showed that two lineage IIIA-2 strains had reduced pathogenicity, while the other lineage III strains had comparable virulence to lineages I and II. The HIB strains are phylogenetically distinct from other sub-populations, providing additional evidence that this sublineage represents a novel lineage. The two biochemical reactions L-rhamnose and L-lactate alkalinization, and 10 internalins were identified as potential markers for lineage III subpopulations. This study provides new insights into the biodiversity and population structure of lineage III strains, which are important for understanding the evolution of the L. mono-cytogenes-L. innocua clade. © 2011 The Microbiological Society of Korea and Springer-Verlag Berlin Heidelberg.


Jiang J.,Shihezi University | Jiang J.,Zhejiang University | Jiang J.,Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine | Chen J.,Zhejiang University | And 12 more authors.
World Journal of Microbiology and Biotechnology | Year: 2011

The LPXTG internlin gene inlC2 is L. monocytogenes specific and formed an internalin cluster with inlD, inlE and, in some cases, inlG between ascB and dapE. Of note, inlC2 was transcribed monocistronically, and of these internalin genes, only inlC2 expression was enhanced in synthetic human gastric fluid. Disruption of inlC2 did not have a polar effect on its downstream internalin genes, but enhanced the production of InlA without changing inlA transcript level, suggesting a link between inlC2 expression and inlA posttranscriptional regulation. The adhesion and invasion rates of ΔinlC2 mutant in epithelial cells were significantly higher than those of parent strain. Also, recovery of listerial cells from the liver and spleen was much higher in mice inoculated with ΔinlC2 mutant than its parent strain. Thus, we speculate that increased invasion of ΔinlC2 mutant into epithelial cells might be due to elevated production of InlA, a major invasin, that could lead further to increased listerial virulence. Overall, this study presents supportive evidence that internalization of L. monocytogenes could be a complex network or unknown mechanisms requiring further study. © 2011 Springer Science+Business Media B.V.

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