Insights into the Genetic Relationships Between Environmental and Clinical Strains of Yersinia enterocolitica Biovar 1A

Abstract

Yersinia enterocolitica, an important food- and water-borne gastrointestinal agent is currently regarded as an emerging pathogen worldwide. Y. enterocolitica is represented by six biovars (1A, 1B, 2, 3, 4 and 5) and more than 70 serotypes. Biovar 1A strains have generally been regarded as nonpathogenic as they lack pYV (plasmid for Y ersinia virulence) plasmid and major chromosomal virulence genes. Despite the lack of known virulence determinants, some biovar 1A strains are associated with the disease indistinguishable from that produced by known pathogenic biovars (1B, 2–5). Genotyping of Yersinia enterocolitica biovar 1A revealed two clonal groups (A and B). Multilocus variable number tandem repeat analysis (MLVA) not only supported the genotyping data but also revealed that wastewater isolates represent the ancestral group while the clinical isolates originated from them. Further, multilocus enzyme electrophoresis (MLEE) revealed the genetic relationships among strains of Y. enterocolitica biovar 1A, and clustered these into four groups. Multilocus restriction typing (MLRT) data also clustered biovar 1A strains into two clonal groups (A and B). The analysis of MLRT data by BURST (Based Upon Related Sequence Types) programme revealed that wastewater isolates represent the ancestral strains while the clinical isolates occupied radial position as single locus variants. All these studies suggested that the clinical strains probably originated from the wastewater strains, by host adaptation and genetic change. Proteomic analysis using whole cell protein profiling displayed sufficient diversity among strains of Y. enterocolitica biovar 1A, and the phylogenetic relationships obtained were in good agreement as established by genotyping techniques. Some pathogenic determinants have also been identified by suppression subtractive hybridization between wastewater and clinical strains. In future, further studies on pathogenic markers of Y. enterocolitica biovar 1A need to be undertaken. So, this would help us in understanding the pathogenic potential and true public health significance of Y. enterocolitica biovar 1A.