Yersinia

Question 1

What family is the genus Yersinia part of

Answer 1

Enterobacteriaceae

Question 2

What do Yersinia species look like

Answer 2

Gram negative, rod shaped bacilli

Question 3

What are the 3 human pathogenic Yersinia species

Answer 3

•Y enterocolitica
•Y pseudotuberculosis
•Y pestis

Question 4

What disease does Y. enterocolitica cause

Answer 4

•yersiniosis
•gastroenteritis, terminal ileitis, mesenteric lymphadenitis, septicemia

Question 5

How is Y enterocolitica transmitted

Answer 5

•faecal oral route
•consumption of contaminated pork or milk
•pigs are reservoir

Question 6

What are the Y enterocolitica biogroups

Answer 6

1A, 1B, 2, 3, 4, 5

Differentiated by biochemical tests

Question 7

What symptoms does Y. pseudotuberculosis cause

Answer 7

•acute gastroenteritis, mesenteric lymphadenitis, diarrhoea, mimics appendicitis

Question 8

Where is Y pseudotuberculosis found

Answer 8

•rodents, rabbits, deer, farm animals, birds
•water

Question 9

What are the 21 serological groups of Y pseudotuberculosis based on

Answer 9

Variations of its lipopolysaccharides

Question 10

What disease does Y pestis cause

Answer 10

•the plague
•severe, acute, rapidly progressing febrile illness

Question 11

Which Yersinia species has a sylvatic life cycle

Answer 11

Y pestis

Question 12

What are the 3 manifestations of the plague

Answer 12

•bubonic
•septicaemic
•pneumonic

Question 13

Justinian plague

Answer 13

•AD542 - AD570
•70,000 dead, 2 years
•started in central Africa -> Egypt -> Mediterranean

Question 14

The black death

Answer 14

•14th - 16th centuries
•30 million dead
•started in Asia -> Crimea -> Europe and Russia

Question 15

The third plague pandemic

Answer 15

•mid 19th century, 1890, China
•12.5 million dead

Question 16

Plague in India, 1994

Answer 16

Bubonic
•August, Maharashtra, Beed district
•deaths of domestic rats in Surat city

Pneumonic
•September, Gujarat, Surat
•10 deaths and 50 ill in like, 1 day

> 6300 cases
•876 serologically positive
•54 deaths

Question 17

How is plague transmitted

Answer 17

•flea bite
•inhalation of infected droplets
•direct contact with contaminated tissue or fluid

Question 18

What are the initial symptoms of plague

Answer 18

•headache, nausea, aching joints, malaise

Question 19

Bubonic plague

Answer 19

•buboes, painful inflammations of lymph nodes (neck, armpit, groin)
•very high fever and delirium
•50-60% die after 4 days

Question 20

Pneumonic plague

Answer 20

•inhalation of droplets -> bacteria enter lungs
•coughing, expulsion of slimy sputum with blood, free flowing red sputum at later stages
•95-100% lead to death in 2-3 days

Question 21

Septicemic plague

Answer 21

•bacteria enter bloodstream
•high fever, rash, gangrene, respiratory failure
•victims turn deep red/black
•100% fatality

Question 22

Which plasmid is F1 capsular antigen encoded by

Answer 22

pMT1 (pFra) plasmid

Question 23

F1 capsular antigen

Answer 23

•forms polypeptide on surface at 37°C
•visible by light microscope
•antiphagocytic

Question 24

Is the F1 capsular antigen a good vaccine candidate

Answer 24

•yes, it’s antigenic
•its important but not essential for virulence

Question 25

Which operon encodes for F1 antigen

Answer 25

•caf operon •also found in E coli and salmonella

Question 26

Which plasmid is Yersinia murine toxin (Ymt) found on

Answer 26

pMT1 (pFra)

Question 27

What does Ymt do

Answer 27

•has phospholipase D activity (PLD) •intracellular PLD protects Y pestis from digestion •enables Y pestis to colonise flea gut

Question 28

What does plasminogen activator do

Answer 28

•transmembrane protease •encoded on pPCP1 •interacts and cleaves host protein targets •these targets are important to infection response •allows bacteria to disseminate and subvert immune response

Question 29

Which secretion system is present in all 3 pathogenic Yersinia

Answer 29

T3SS

Question 30

Which plasmid is the T3SS encoded on in pathogenic Yersinia

Answer 30

pCD1 plasmid

Question 31

How is the T3SS expression activated in pathogenic Yersinia

Answer 31

•temperature change to 37°C •presence of calcium

Question 32

Yersinia T3SS functions

Answer 32

•inject multiple toxic Yersinia effector proteins (Yops) directly into host •subvert host cell signalling •trigger apoptosis or cell death •inhibit phagocytosis •suppress immune cells

Question 33

T3SS and translocon in Yersinia

Answer 33

•injectisome •needle fixed into bacterial inner and outer membrane •protrudes from surface and penetrates host cell •translocon forms channel through host membrane •Yop effectors transferred into host

Question 34

Which antigen is essential for Yersinia virulence

Answer 34

LcrV •low calcium response •lack of LcrV leads to secretion into extracellular environment •LcrV or V antigen confers resistance to phagocytosis

Question 35

Low calcium response of Yersinia

Answer 35

•Yersinia grown at 37°C in media containing <1mM of Ca have arrested growth •secrete high levels of proteins into growth medium

Question 36

Direct delivery of Yops

Answer 36

•yersinia outer proteins (Yops) •mutants deficient in LcrV not cytotoxic •secreted proteins are not cytotoxic •but injection of proteins leads to cytotoxicity

Question 37

Yersinia invasins

Answer 37

•chromosomally encoded adhesins •mediates attachment to and entry into host •present in Y pseudotuberculosis and Y enterocolitica •pseusogene in pestis •small intestinal epithelial internalisation by binding to beta1 integrins •integrins form clusters resulting in rearrangement of host cytoskeleton •phagocytosis

Question 38

YadA

Answer 38

•expression induced at 37°C •non fimbrial adhesin •required for Y enterocolitica pathogenicity •not essential for Y pseudotuberculosis •pseudogene in pestis