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Plasmid content in Yersinia pestis strains of different origin
A A Filippov1, N S Solodovnikov, L M Kookleva
1Department of Genetics, All-Union Research Anti-Plague Institute, Microbe, Saratov, U.S.S.R.
Abstract:
Plasmid content in 242 Yersinia pestis strains from various natural plague foci of the U.S.S.R. and other countries was studied. Of these strains, 172 (71%) were shown to carry three plasmids described previously of about 6, 45-50 and 60 MDa, respectively. Twenty strains (8%) from different foci harboured additional cryptic plasmids, most often of about 20 mDa in size. Plasmid pPst displayed considerable constancy of its molecular mass. On the contrary, size variations of pCad (45-49 MDa) and, especially, pFra (60-190 MDa) were found. Molecular mass of these plasmids correlated with the host strain origin.
Insights
Most Yersinia pestis strains carry three key plasmids. Variations in plasmid size, particularly pFra, were observed and linked to the host strain
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Yersinia pestis is the causative agent of plague.
- Plasmids play a crucial role in the virulence and adaptability of Yersinia pestis.
- Understanding plasmid diversity is essential for tracking plague epidemiology.
Purpose of the Study:
- To investigate the plasmid content of a large collection of Yersinia pestis strains.
- To identify common and novel plasmids within these strains.
- To analyze variations in plasmid molecular mass and their correlation with geographic origin.
Main Methods:
- Plasmid DNA extraction from 242 Yersinia pestis strains.
- Agarose gel electrophoresis to determine plasmid size and number.
- Comparison of plasmid profiles across strains from different geographic locations.
Main Results:
- 71% of strains harbored the three previously described plasmids (6, 45-50, and 60 MDa).
- 8% of strains carried additional cryptic plasmids, predominantly around 20 MDa.
- Plasmid pPst showed consistent molecular mass, while pCad and pFra exhibited significant size variations (pFra: 60-190 MDa).
- Plasmid molecular mass correlated with the host strain's origin.
Conclusions:
- The three core plasmids are highly conserved in Yersinia pestis.
- Plasmid size variation, especially in pFra, may reflect adaptation to different environmental niches or host interactions.
- Geographic origin is a significant factor influencing the plasmid profiles of Yersinia pestis strains.