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Bubonic plague: a molecular genetic case history of the emergence of an infectious disease
1Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
Abstract:
Yersinia pestis, the bacterial agent of bubonic plague, is transmitted primarily by fleas and has been responsible for devastating epidemics throughout history. Y. pseudotuberculosis is a food- and water-borne pathogen that causes a much more benign enteric disease in humans. Despite these profoundly different pathogenesis strategies, the two bacteria are very closely related phylogenetically. Thus, identifying the specific genetic differences between them should provide an instructive case study in the evolution of microbial pathogenicity. Some key pathogenesis-related genes of Y. pestis and Y. pseudotuberculosis that have been described to date are compared in this review. Factors that potentiate plague transmission as well as disease are discussed, since dependence on the blood-sucking flea for transmission likely fueled the selection of virulent Y. pestis strains able to produce a high-density bacteremia. Retracing the evolutionary steps between these two Yersinia species may ultimately furnish a historical model for the sudden emergence of new human disease agents.
Insights
Comparing Yersinia pestis and Yersinia pseudotuberculosis reveals genetic differences driving distinct disease outcomes. This evolutionary study offers insights into the emergence of new infectious agents.
Area of Science:
- Microbiology
- Evolutionary Biology
- Pathogenesis
Background:
- Yersinia pestis causes bubonic plague via flea transmission, leading to historical epidemics.
- Yersinia pseudotuberculosis is a food-borne pathogen causing milder enteric illness.
- Despite differing pathogenesis, these bacteria are phylogenetically close, making them ideal for studying pathogenicity evolution.
Purpose of the Study:
- To identify genetic distinctions between Y. pestis and Y. pseudotuberculosis.
- To explore evolutionary pathways of microbial pathogenicity.
- To understand factors influencing plague transmission and virulence.
Main Methods:
- Comparative review of key pathogenesis-related genes in Y. pestis and Y. pseudotuberculosis.
- Analysis of factors potentiating plague transmission and disease.
- Phylogenetic comparison of the two Yersinia species.
Main Results:
- Key genetic differences contributing to distinct pathogenic strategies were identified.
- The role of flea-borne transmission in selecting for virulent Y. pestis strains was highlighted.
- Evolutionary divergence points between the species were elucidated.
Conclusions:
- Genetic variations between Y. pestis and Y. pseudotuberculosis are crucial for their differing pathogenicity.
- Understanding these evolutionary steps provides a model for the emergence of novel human pathogens.
- This comparative study enhances knowledge of bacterial evolution and disease emergence.