The genus Yersinia belongs to the Enterobacteriaceae family and is composed of 17 species, three of which are pathogenic for humans: Y. enterocolitica, Y. pseudotuberculosis and Y. pestis.
Y. enterocolitica and Y. pseudotuberculosis are widespread among various animal species and in the environment. They are transmitted to humans by the oral route and cause intestinal symptoms such as abdominal pain, diarrhea and fever. They are most often responsible for sporadic cases in France. These species are found all over the world, with a higher incidence in temperate and cold countries. Y. enterocolitica is the third etiological agent of bacterial diarrhea in France and in Europe. The importance of Y. pseudotuberculosis in human infections is much lower than that of Y. enterocolitica in most countries, except in Russia, Finland and Japan.
The plague bacillus
Y. pestis is the causative agent of plague. This zoonotic disease is transmitted from animal to humans by fleabites. Bubonic plague, the most common clinical form of plague, is characterized by the development of a painful lymph node (bubo) in the area draining the bite site. From the bubo, Y. pestis disseminates by hematogenous route to deeper tissues (liver, spleen, lungs, central nervous system), leading to the death of 50-70% of the patients in less than a week in the absence of treatment. Pneumonic plague results from interhuman contamination through aerosol transmission and is characterized by an acute and highly severe pneumopathy. Without early and effective antibiotherapy, this form of plague is systematically lethal in usually less than three days. Y. pestis is one of nature’s most pathogenic bacteria for humans. Despite considerable progress in plague prevention and cure, this infection has not been eradicated and natural plague foci are found in numerous countries in Africa, in Asia and in the Americas (including the USA). Because of the steady increase in reported cases during the past 20 years and the reappearance of the disease in areas otherwise declared plague-free for several decades, the plague has been included in the list of re-emerging diseases.
The activities of the Yersinia Research Unit are primarily devoted to the analysis of:
– Mechanisms of horizontal gene transfer in Yersinia.
– Comparative genomics and transcriptomics between Y. pestis and Y. pseudotuberculosis.
– Molecular bases for the exceptional pathogenicity of Y. pestis.
– Pathophysiology of Yersinia infections.
– Host’s mechanisms of innate and adaptive immunity.
– Genetic bases of host susceptibility to plague.
– Resistance of pathogenic Yersinia to antibiotics.
– Evolution of pathogenic Yersinia.
The Unit is also developing:
– A vaccine against plague and pseudotuberculosis.
– Typing tools for molecular epidemiology.
– Real time in vivo imaging technology to follow the kinetics of Y. pestis development in its host.
– Tools for stable gene complementation and gene expression in vitro and in vivo.
– Techniques for molecular characterization of the various Yersinia species.
The Unit participates actively to the surveillance and control of enteropathogenic Yersinia through its activities at the National level (Reference Laboratory and French Surveillance Network), and to the fight against plague at the international level (World Health Organization Collaborating Center for Yersinia).