11. Yersinia

Question 1

What disease does Yersinia spp. cause?

Answer 1

Food poisoning, plague

Question 2

How does Yersinia spp. cause disease?

Answer 2

Invasion, vector borne, T3SS

Question 3

Features of Yersinia?

Answer 3

• Vector borne
• Gram neg
• Rod-shaped
• Psychrotrophic (like low temperatures)
• Enterobacteriaceae (Shigella, E.coli, Salmonella)

Question 4

Examples of psychrotrophic pathogens?

Answer 4

Listeria monocytogenes, Yersinia spp.

Question 5

Which family is Yersinia part of?

Answer 5

Enterobacteriaceae

Question 6

Which strains of Yersinia cause food poisoning (yersiniosis)?

Answer 6

Yersinia entercolitica &
Yersinia pseudotuberculosis
- food or waterborne

Question 7

Which strain of Yersinia causes plague/Black Death?

Answer 7

Yersinia pestis

Tick borne , reservoirs in rodents
Animals (swine, rats, ticks [plague])

Question 8

Yersiniosis symptoms?

Answer 8

Diarrhoea, abdominal pain, fever, appendicitis-like

Question 9

Pathogenesis of Yersinia enterocolitica & pseudotuberculosis

Answer 9

• Both invasive
• Both species are transmitted through M cells
• Cause a localised inflammatory response - cause symptoms
• Eventually eliminated by PMNs (white blood cells)

Question 10

Sequelae of yersiniosis?

Answer 10

Can have a complication of Reiter’s Syndrome (an autoimmune response due to cross-reaction between Abs & host Ags

Question 11

Many of the Yersinia virulence traits are encoded by a large virulence plasmid (pCD1 or pYV). The plasmid encodes 4 main gene categories:

Answer 11

1. Adhesin/invasion: YadA - adhesin which can force uptake (by M cells)
2. Iron uptake: high pathogenicity island (HPI)(Yersiniobactin - siderophore)
3. Antiphagocytic proteins: Yops (>11), delay phagocytosis, Ysc (encodes the T3SS) exports Yops via the T3SS
4. Regulatory proteins: Lcr - regulates all the genes

Question 12

What is the YadA adhesive protein important in?

Answer 12

Binds to collagen

Serum resistance - inhibits the classical pathway of complement activation

Question 13

Discuss the T3SS in Yersinia

Answer 13

• 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

Question 14

Toxin produced by Yersinia?

Answer 14

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

Question 15

Treatment for yersiniosis?

Answer 15

Usually self-limiting for gastroenteritis

• wait it out

Question 16

What causes the Bubonic Plague/Black Death?

Answer 16

Yersinia pestis

Question 17

How is the Black Death acquired?

Answer 17

Via insect bites or person to person contact

Bacteria enter bloodstream and travel to the lymph nodes where they cause swelling

Question 18

3 types of plague?

Answer 18

• Bubonic plague: most common, infection of the lymph system, swollen LNs
• Pneumonic plague: most serious, infection of lung macrophages that leads to pneumonia, primary and secondary, high transmissibility & fatality
• Septicaemic plague: bacteria reproduce in blood, characterised by LPS shock, contracted like bubonic plague but is most often seen as a complication of untreated bubonic or pneumonic plague

Question 19

Large outbreaks of plague would be associated with large numbers of which type of plague?

Answer 19

Pneumonic plague

Question 20

Difference between primary and secondary pneumonic plague?

Answer 20

Primary - contracted when infected droplets are directly inhaled (can be passed from person to person)
Secondary - develops when bubonic or septicaemic goes untreated (moves to lungs and then can be spread to someone else)

Question 21

How is plague usually treated?

Answer 21

By Streptomycin

Question 22

3 strains of Yersinia?

Answer 22

Y. enterocolitica
Y. pseudotuberculosis
Y. pestis

Question 23

What is Yersinia commonly mistaken for?

Answer 23

Appendicitis

• abdominal pain
• fever

Question 24

True of false: Yersinia is part of the normal human flora.

Answer 24

False

Question 25

Is YadA an important virulence factor in all strains?

Answer 25

- Important virulence factor in Y. enterocolitica - Dispensable in Y. pseudoTB - Pseudogene in Y. pestis

Question 26

How is Y.pestis spread

Answer 26

Rodent population have it, are fed on by fleas, fleas pick it up, rodents all die because of it, fleas have no food, feed on humans → plague

Question 27

How many plague pandemics have there been? How many deaths were caused?

Answer 27

1. Justinian Plague 2. Black Death (most severe) 3. Chinese province of Yunnnan 200 million deaths

Question 28

How do we know Y. pestis was responsible for Justinian Plague?

Answer 28

Plague graves fin Bavaria, radiocarbon dating, DNA extracted from teeth, DNA was enriched with Y. pestis and sequenced, confirmed presence

Question 29

Death toll of Justinian Plague?

Answer 29

Killed 50-60% of European population

Question 30

Death toll of black plague?

Answer 30

50% of European population - 25 million 50% of China population - 60 million, 70% in Muslim world

Question 31

Plague in Ireland

Question 32

What is the most recent outbreak of Plague?

Answer 32

Madagascar November 2017 | 2348 cases, 202 deaths

Question 33

What plasmids is Y. pestis host to?

Answer 33

``` Plasmid pCD1 (pYV) and two others, plasmid pPCP1 (pPla/pPst) and pMT1 (pFra) which are not carried by Yersinia species ```

Question 34

What did Y. pestis emerge from?

Answer 34

Y. pseudotuberculosis (20,000 years ago)

Question 35

True or False: Y. pestis contains many of the same genes as Y. pseudotuberculosis

Answer 35

TRUE - Pseudogenes- Y. pestis has same genes as YP but they aren’t expressed - Over 150 of these, including YadA - One way via which these bacteria can rapidly evolve

Question 36

Symptoms of Bubonic plague

Answer 36

Fever, headache, chills, weakness, swollen and tender lymph glands

Question 37

Symptoms of Pneumonic plague

Answer 37

Fever, headache, weakness, rapid onset of pneumonia (usually accompanied by: shortness of breath, chest pain, cough, bloody or watery sputum)

Question 38

Symptoms of Septicemic plague

Answer 38

Fever, chills, weakness, abdominal pain, shock, bleeding underneath skin or other organs