All Yersinia enterocolitica are pathogenic: virulence of phylogroup 1 Y. enterocolitica in a Galleria mellonella infection model.

Yersinia enterocolitica is a zoonotic pathogen and a common cause of gastroenteritis in humans. The species is composed of six diverse phylogroups, of which strains of phylogroup 1 are considered non-pathogenic to mammals due to the lack of the major virulence plasmid pYV, and their lack of virulence in a mouse infection model. In the present report we present data examining the pathogenicity of strains of Y. enterocolitica across all six phylogroups in a Galleria mellonellla model. We have demonstrated that in this model strains of phylogroup 1 exhibit severe pathogenesis with a lethal dose of as low as 10 c.f.u., that this virulence is an active process and that flagella play a major role in the virulence phenotype. We have also demonstrated that the complete lack of virulence in Galleria of the mammalian pathogenic phylogroups is not due to carriage of the pYV virulence plasmid. Our data suggest that all Y. enterocolitica can be pathogenic, which may be a reflection of the true natural habitat of the species, and that we may need to reconsider the eco-evo perspective of this important bacterial species.