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Chapter 14 : Yersinia enterocolitica
Category: Applied and Industrial Microbiology; Food Microbiology
Yersinia enterocolitica is an invasive enteric pathogen whose virulence determinants have been the subject of intensive investigation, but not all strains of Y. enterocolitica are equally virulent. Schemes for subtyping Yersinia species include bacteriophage typing, multienzyme electrophoresis, multilocus sequence typing, and the demonstration of restriction fragment length polymorphisms of chromosomal and plasmid DNA. As the mechanisms by which biotype 1A strains cause disease are largely unknown, a section of this chapter focuses chiefly on the virulence determinants of the classical pathogenic, i.e., pYV-bearing, highly invasive strains of Y. enterocolitica. As with other enterobacteria, Y. enterocolitica can be classified as smooth or rough depending on the amount of O side chain polysaccharide attached to the inner core region of the cell wall lipopolysaccharide (LPS). The major receptor for ferri-yersiniabactin complex is a 65-kDa outer membrane protein named FyuA, which also serves as a receptor for pesticin, a bacteriocin produced by Y. pestis. The effector, Yops, achieve these outcomes mostly by disrupting the proinflammatory signaling pathways that are activated in response to stimulation by invasin, YadA, and LPS. Although much remains to be learned about Y. enterocolitica, investigations into the pathogenesis of yersiniosis to date have provided fascinating new insights into bacterial pathogenesis as a whole and into its genetic control.
Transmission electron micrograph showing the initial interaction (arrowhead) and transport (arrow) of Y. enterocolitica through an intestinal M cell 60 min after inoculation into mouse ileum. (Reprinted with permission from reference 83 .)
Light micrograph of a section through the colon of a gnotobiotic piglet 3 days after inoculation with a virulent strain of Y. enterocolitica O:3. Note the microabscess, comprising mostly bacteria, the surrounding inflammatory cells (arrows), and the disrupted epithelium with vacuolated and necrotic cells. An epoxy section stained with methylene blue is shown. (Reprinted with permission from reference 230 .)
Amino acid sequences of the mature heat-stable enterotoxins produced by Y. enterocolitica ( 102 , 173 , 221 ), enterotoxigenic E. coli (human [STh] and porcine [STp] subtypes) ( 7 , 219 ), C. freundii ( 84 ), and non-O1 V. cholerae ( 220 ) and of the intestinal hormone guanylin ( 50 ). Amino acid residues which are shaded are common to all seven peptides. The first 23 amino acids at the N terminus of the Yst-c mature toxin (denoted by a superscript “a”) are not included in the sequence alignment.
Representation of the HPI of Y. enterocolitica O:8 strain WA-C. Arrows indicate the positions of the open reading frames and the direction of transcription. The region that is conserved in Y. pestis and Y. pseudotuberculosis is indicated by a double-headed arrow. (Adapted from reference 169 .)
Map of the virulence plasmid, pYVe, of Y. enterocolitica serogroup O:9 showing the locations and directions of transcription (arrows) of the genes encoding (i) YadA; (ii) YlpA; (iii) YopB, -D, -E, -H, -M, -N, -O, -P, -Q, and -T and LcrV; (iv) the specific Yop chaperones SycD, -E, -H, and -T; (v) the secretion elements VirA, -B, -C, and -G; and (vi) the regulatory element VirF. (Adapted from reference 103 .)
Schematic representation of Yop secretion and translocation by Y. enterocolitica. The major structural proteins of the secretory apparatus are shown in relation to their known or deduced locations in the cell wall. The effector Yop chaperone (Syc) and a translocation pore comprising YopB and YopD are also depicted.
Antibody response of sheep infected with Y. enterocolitica or Y. pseudotuberculosis to Yops. Yops were prepared from Y. enterocolitica serogroup O:3, separated by polyacrylamide gel electrophoresis, transferred to a nitrocellulose membrane, and incubated with preimmune (lanes 1 and 3) or immune (lanes 2 and 4) sera from lambs with naturally acquired infection with pYV-bearing Y. enterocolitica (lanes 1 and 2) or Y. pseudotuberculosis (lanes 3 and 4). (Reprinted with permission from reference 174 .)
Some biochemical tests used to differentiate Yersinia species a
Biotyping scheme for Y. enterocolitica a
Relationship between O serotype and pathogenicity of Y. enterocolitica and related species
Clinical manifestations of infections with Y. enterocolitica
Selected foodborne outbreaks of infections with Y. enterocolitica
Characteristics of pathogenic subgroups of Y. enterocolitica
Major pYV-encoded determinants of Y. enterocolitica and their roles in virulence