Possible use of ail and foxA polymorphisms for detecting pathogenic Yersinia enterocolitica

Yersinia enterocolitica is an enteric pathogen that invades the intestinal mucosa and proliferates within the lymphoid follicles (Peyer's patches). The attachment invasion locus (ail) mediates invasion by Y. enterocolitica and confers an invasive phenotype upon non-invasive E. coli; ail is the primary virulence factor of Y. enterocolitica. The ferrioxamine receptor (foxA) located on the Y. enterocolitica chromosome, together with its transport protein, transports a siderophore specific for ferric ion. Currently, ail is the primary target gene for nucleic acid detection of pathogenic Y. enterocolitica.

The genes ail and foxA in 271 pathogenic and 27 non-pathogenic Y. enterocolitica strains isolated from China and 10 reference strains were sequenced, aligned, compared to the ail and foxA sequences of Yersinia enterocolitica subsp. enterocolitica 8081 (Genbank: NC_008800), and analyzed for sequence polymorphism. The ail from the 282 strains showed 3 sequence patterns: 277 strains of serotypes O:3, O:9 and O:5, 27 with identical nucleic acid sequences formed pattern A1; 4 strains of serotype 1B/O:8 with identical nucleic acid sequences formed pattern A2; and one Chinese isolate 2/O:9 formed pattern A3. In the primary coding region of the foxA ORF (Genebank: X60447 nt 433-1866; nt 28 to 1,461 in the ORF), the sequences formed 3 groups and were further divided into 8 sequence patterns.

The ail and foxA loci of pathogenic Y. enterocolitica have been analyzed. The ail sequence was highly conserved among the same serotype strains from different sources; and foxA was highly conserved among the pathogenic strains, although there was some sequence diversity. Fewer strains were used from outside China, which is a limitation of the study.