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Diagnostic value of plasmid analyses and assays for virulence in Yersinia enterocolitica
Abstract:
The possession of a 42- to 48-megadalton plasmid alone does not appear to be predictive of virulence in Yersinia species. Twelve of 100 Yersinia enterocolitica strains contained a 42 to 48-megadalton plasmid, and 4 of 30 Y. enterocolitica-like strains contained a 42- to 48-megadalton plasmid. Seven strains of Y. enterocolitica contained the 42- to 48-megadalton plasmid plus an 82-megadalton plasmid, and these were the only study strains lethal for mice. Based on restriction endonuclease digestion, the 42- to 48-megadalton plasmid DNA from these seven strains were similar and were not similar to the 42- to 48-megadalton plasmids present in the other nine strains. The ability to invade guinea pig eye tissues, calcium dependency, autoagglutination, and colonial morphology at 37 degrees C were also associated with plasmid DNA, but the relationships were either variable or not reciprocal. Neither tissue culture invasiveness nor heat-stable toxin production was associated with plasmid DNA. It was concluded that biochemical speciation and a total plasmid profile in combination with enzyme digests are predictive of virulence in Y. enterocolitica as it is measured by mouse lethality.
Insights
Virulence in Yersinia species is not predicted by a single 42- to 48-megadalton plasmid. Lethality in mice was associated with this plasmid combined with an 82-megadalton plasmid.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Yersinia species are significant human pathogens.
- Plasmid DNA is often associated with bacterial virulence factors.
- The role of specific plasmids in Yersinia virulence requires further elucidation.
Purpose of the Study:
- To investigate the predictive value of plasmid DNA for virulence in Yersinia species.
- To determine the relationship between specific plasmids and virulence traits, including mouse lethality.
Main Methods:
- Analysis of plasmid profiles in Yersinia enterocolitica and related strains.
- Restriction endonuclease digestion to characterize plasmid DNA.
- Assessment of virulence-associated phenotypes: mouse lethality, guinea pig eye invasiveness, calcium dependency, autoagglutination, and colonial morphology at 37°C.
Main Results:
- A 42- to 48-megadalton plasmid alone did not predict virulence.
- Seven Yersinia enterocolitica strains possessing both a 42- to 48-megadalton and an 82-megadalton plasmid were lethal to mice.
- The 42- to 48-megadalton plasmids from lethal strains were similar to each other but distinct from those in non-lethal strains.
- Other virulence traits showed variable or non-reciprocal associations with plasmid DNA.
Conclusions:
- Biochemical speciation combined with a comprehensive plasmid profile and enzyme digests can predict Yersinia enterocolitica virulence in mouse lethality models.
- The presence of both a 42- to 48-megadalton and an 82-megadalton plasmid is a strong indicator of virulence in Yersinia enterocolitica.