About Yersinia Pestis

Yersinia pestis is a Gram-negative bacterium belonging to the Enterobacteriaceae clade. It is the agent of plague. It infects wild rodents which act as a reservoir for flea-transmitted dissemination of plague to anthropophilic rodents and eventually patients. Infection resulting from flea-borne Yersinia pestis features bubonic plague, eventually leading to septicemia, secondary pneumonia and death. Exceptionally, low efficient air-borne transmission results in primary pneumonic plague. Untreated plague is a deadly infection and Yersinia pestis has been classified as a group A bioterorrism agent. Yersinia pestis has been responsible for three historical pandemics, Justinian plague in 6-8th century, Black Death in 14-18th century and current pandemic which started in 1894 in Yunan and then swept all over the world.

Three Yersinia pestis biotypes have been recognized on the basis of their abilities to convert nitrate to nitrite and ferment glycerol. The biotype Antiqua has both characteristics. The biotype Medievalis ferments glycerol but does not form nitrite. Yersinia pestis Orientalis forms nitrite but does not ferment glycerol. A fourth biotype microtus has been proposed to accomodate Chineese isolates differing from Medievalis by the inability to ferment arabinose.

Yersinia pestis evolved 2,000-20,000 years ago as an unique clone from a common ancestor with Yersinia pseudotuberculosis, explaining the weak diversity of this species. Various typing methods have been proposed to discriminate among Yersinia pestis isolates. Pulsed field gel electroporesis (PFGE) analysis has been used for biovar and strain differentiation but it requires large amounts of cultured microorganisms and the stability of PFGE profiles in subculture has been questioned. Ribotyping did not classified isolates into their respective biovars. Specific insertion sequences (IS), including IS 100, IS 285 and IS 1541 were used as markers in restriction fragment length polymorphism (RFLP) analysis and in PCR-based analysis. The last approach produced identical patterns of IS 100 distribution in Antiqua and Medievalis isolates. A variable number tandem repeat (VNTR) technique had a greater discrimination capacity than did ribotyping but isolates from different areas were found to harbor identical types. At last, sequencing five housekeeping genes in Yersinia pestis isolates from various locations did not show diversity.

MST using eight variable spaces sequences between the two Yersinia pestis genomes available at initiation of our work, identified 19 genotypes among 36 tested isolates from various locations. The MST classification matched the phylogenetic organization of isolates and MST proved the most discriminatory genotyping method to date for Yersinia pestis.

Publication

• 2004-09-01Genotyping, Orientalis-like Yersinia pestis, and plague pandemicsDrancourt M, Roux V, Dang LV, Tran-Hung L, Castex D, Chenal-Francisque V, Ogata H, Fournier PE, Crubézy E, Raoult D