TheYersinia pestis caf1M1A1Fimbrial Capsule Operon Promotes Transmission by Flea Bite in a Mouse Model of Bubonic Plague
Open Access
- 1 March 2009
- journal article
- research article
- Published by American Society for Microbiology in Infection and Immunity
- Vol. 77 (3), 1222-1229
- https://doi.org/10.1128/iai.00950-08
Abstract
Plague is a zoonosis transmitted by fleas and caused by the gram-negative bacterium Yersinia pestis. During infection, the plasmidic caf1M1A1 operon that encodes the Y. pestis F1 protein capsule is highly expressed, and anti-F1 antibodies are protective. Surprisingly, the capsule is not required for virulence after injection of cultured bacteria, even though it is an antiphagocytic factor and capsule-deficient Y. pestis strains are rarely isolated. We found that a caf-negative Y. pestis mutant was not impaired in either flea colonization or virulence in mice after intradermal inoculation of cultured bacteria. In contrast, absence of the caf operon decreased bubonic plague incidence after a flea bite. Successful development of plague in mice infected by flea bite with the caf-negative mutant required a higher number of infective bites per challenge. In addition, the mutant displayed a highly autoaggregative phenotype in infected liver and spleen. The results suggest that acquisition of the caf locus via horizontal transfer by an ancestral Y. pestis strain increased transmissibility and the potential for epidemic spread. In addition, our data support a model in which atypical caf-negative strains could emerge during climatic conditions that favor a high flea burden. Human infection with such strains would not be diagnosed by the standard clinical tests that detect F1 antibody or antigen, suggesting that more comprehensive surveillance for atypical Y. pestis strains in plague foci may be necessary. The results also highlight the importance of studying Y. pestis pathogenesis in the natural context of arthropod-borne transmission.Keywords
This publication has 84 references indexed in Scilit:
- Biogenesis of the Fraction 1 Capsule and Analysis of the Ultrastructure of Yersinia pestisJournal of Bacteriology, 2008
- The fraction 1 and V protein antigens of Yersinia pestis activate dendritic cells to induce primary T cell responsesClinical and Experimental Immunology, 2007
- Early-phase transmission of Yersinia pestis by unblocked fleas as a mechanism explaining rapidly spreading plague epizooticsProceedings of the National Academy of Sciences, 2006
- Adaptive response of Yersinia pestis to extracellular effectors of innate immunity during bubonic plagueProceedings of the National Academy of Sciences, 2006
- Poor Vector Competence of Fleas and the Evolution of Hypervirulence inYersinia pestisThe Journal of Infectious Diseases, 2005
- Transmission ofYersinia pestisfrom an Infectious Biofilm in the Flea VectorThe Journal of Infectious Diseases, 2004
- Specific high affinity binding of human interleukin 1β by Caf1A usher protein of Yersinia pestisFEBS Letters, 1995
- Caf1R gene and its role in the regulation of capsule formation of Y. pestisFEBS Letters, 1992
- A new gene of the ƒ1 operon of Y. pestis involved in the capsule biogenesisFEBS Letters, 1992
- Potential for rat plague from nonencapsulated variants of the plague bacillus (Yersinia pestis)Cellular and Molecular Life Sciences, 1984