11. Yersinia Flashcards
What disease does Yersinia spp. cause?
Food poisoning, plague
How does Yersinia spp. cause disease?
Invasion, vector borne, T3SS
Features of Yersinia?
- Vector borne
- Gram neg
- Rod-shaped
- Psychrotrophic (like low temperatures)
- Enterobacteriaceae (Shigella, E.coli, Salmonella)
Examples of psychrotrophic pathogens?
Listeria monocytogenes, Yersinia spp.
Which family is Yersinia part of?
Enterobacteriaceae
Which strains of Yersinia cause food poisoning (yersiniosis)?
Yersinia entercolitica &
Yersinia pseudotuberculosis
- food or waterborne
Which strain of Yersinia causes plague/Black Death?
Yersinia pestis
Tick borne , reservoirs in rodents
Animals (swine, rats, ticks [plague])
Yersiniosis symptoms?
Diarrhoea, abdominal pain, fever, appendicitis-like
Pathogenesis of Yersinia enterocolitica & pseudotuberculosis
- Both invasive
- Both species are transmitted through M cells
- Cause a localised inflammatory response - cause symptoms
- Eventually eliminated by PMNs (white blood cells)
Sequelae of yersiniosis?
Can have a complication of Reiter’s Syndrome (an autoimmune response due to cross-reaction between Abs & host Ags
Many of the Yersinia virulence traits are encoded by a large virulence plasmid (pCD1 or pYV). The plasmid encodes 4 main gene categories:
- Adhesin/invasion: YadA - adhesin which can force uptake (by M cells)
- Iron uptake: high pathogenicity island (HPI)(Yersiniobactin - siderophore)
- Antiphagocytic proteins: Yops (>11), delay phagocytosis, Ysc (encodes the T3SS) exports Yops via the T3SS
- Regulatory proteins: Lcr - regulates all the genes
What is the YadA adhesive protein important in?
Binds to collagen
Serum resistance - inhibits the classical pathway of complement activation
Discuss the T3SS in Yersinia
- T3SS found in all pathogenic strains of Yersinia
- Classic needle-like structure - made of polymer YscF, with a tip YopB
- Effector proteins (Yop proteins) excreted into cell
- Immunosuppression - dampens immune response of some cells to help colonise & start infection
- Interacts with key signalling pathways
- Antiphagocytic - by interfering with actin rearrangement necessary for phagocytosis
Toxin produced by Yersinia?
Yst: Yersinia stable toxin
similar to E. coli ST (small peptide)
3 variants: ystA, ystB, ystC
*role in virulence of Y.entercolitica not yet established
Treatment for yersiniosis?
Usually self-limiting for gastroenteritis
- wait it out