Lecture 9 - Bacterial Pathogenesis - Adherence, Colonisation

Question 1

What are the stages of bacterial pathogenesis?
1)
2)
3)
4)
5)

Answer 1

1) Enter the body
2) Colonise the host
3) Evade host defences
4) Multiply, disseminate in host
5) Cause damage to host

Question 2

What is the advantage of Strep. pyogenes’ capsule?

Answer 2

Made of hyaluronic acid

Very similar to many host cell surfaces, therefore not readily detected by immune system

Question 3

Feature of bacteria causing very persistent infection

Answer 3

Biofilm formation

Question 4

How is a biofilm formed?

Answer 4

Bacteria aggregate, secrete ECM of protein, polysaccharides, DNA

Question 5

How might a biofilm contribute to antibiotic resistance?
1)
2)

Answer 5

1) Bacteria in biofilm can become inert - antibiotics affect growing or dividing bacteria
2) Barrier between bacteria and antibiotic

Question 6

Where can biofilms be frequently found?
1)
2)
3)
4)
5)

Answer 6

1) Implants
2) Catheters
3) Artificial heart valves
4) Teeth
5) Contact lenses

Question 7

Which bacterium often colonises catheters?

Answer 7

Pseudomonas aeruginosa

Enterococcus

Question 8

Stages of biofilm production
1)
2)
3)
4)
5)

Answer 8

1) Adhesion
2) Colonisation
3) Cell-cell adhesion
4) Proliferation
5) Maturation

Planktonic bacteria leave biofilm, adhere to another structure

Question 9

Which bacteria most commonly cause biofilms on tonsils?

Answer 9

Staph. aureus

Haemophilus influenzae

Question 10

Types of bacterial colonisation
1)
2)
3)

Answer 10

1) Loose association
2) Tight association
3) Invasion

Question 11

Most accessible part of host cell

Answer 11

Glycocalyx

Question 12

Function of b1 integrins

Answer 12

Attach cell cytoskeleton to extracellular matrix

Question 13

Common bacterial target in GIT

Answer 13

M cells

Have much thinner layer of mucus covering them than other parts of GIT

Question 14

What do bacterial adhesins normally target?

Answer 14

Polysaccharide structures

Question 15

Example of host cell protein receptor often bound to by bacterial adhesins

Answer 15

Beta-1 integrin receptor

Question 16

Two types of adhesins

Answer 16

1) Fimbrial adhesins (loose associations)

2) Afimbrial adhesins (outer membrane proteins)

Question 17

Type of bacteria which most commonly have pili

Answer 17

Gram -

Question 18

What do type I pili bind?

Answer 18

Mannose in glycoproteins

Question 19

What do Pap pili do?

Answer 19

Bind Gal alpha(1-4)Gal in glycolipids

Question 20

Requirements of Pap/Type I pili construction

Answer 20

Usher/chaperone system

Question 21

Which bacterium often colonises catheters?

Answer 21

Pseudomonas aeruginosa

Enterococcus

Question 22

Stages of biofilm production
1)
2)
3)
4)
5)

Answer 22

1) Adhesion
2) Colonisation
3) Cell-cell adhesion
4) Proliferation
5) Maturation

Planktonic bacteria leave biofilm, adhere to another structure

Question 23

Which bacteria most commonly cause biofilms on tonsils?

Answer 23

Staph. aureus

Haemophilus influenzae

Question 24

Types of bacterial colonisation
1)
2)
3)

Answer 24

1) Loose association
2) Tight association
3) Invasion

Question 25

How does pilin get moved from cytoplasm to cell surface? 1) 2) 3)

Answer 25

1) Sec is a channel which brings pilin from cytoplasm to periplasmic space 2) Pilin needs to form correct disulphide bonds, find chaperone, or else is degraded 3) Chaperone/protein complex binds usher, usher brings pilin from periplasmic space to cell surface. PIlin is incorporated into pilus

Question 26

Function of b1 integrins

Answer 26

Attach cell cytoskeleton to extracellular matrix

Question 27

Common bacterial target in GIT

Answer 27

M cells | Have much thinner layer of mucus covering them than other parts of GIT

Question 28

What do bacterial adhesins normally target?

Answer 28

Polysaccharide structures

Question 29

Example of host cell protein receptor often bound to by bacterial adhesins

Answer 29

Beta-1 integrin receptor

Question 30

Which pili use a type II secretion system?

Answer 30

Type IV pili

Question 31

Type of bacteria which most commonly have pili

Answer 31

Gram -

Question 32

What do type I pili bind?

Answer 32

Mannose in glycoproteins

Question 33

What do Pap pili do?

Answer 33

Bind Gal alpha(1-4)Gal in glycolipids

Question 34

Requirements of Pap/Type I pili construction

Answer 34

Usher/chaperone system

Question 35

Function of usher protein

Answer 35

1) Usher binds chaperone/pilin complex in periplasmic space. | 2) Pilin moved across cell membrane by usher, attached to pilus

Question 36

Structure of pilus

Answer 36

Composite fibre made up of six structural proteins | Helical array of pilin

Question 37

In pap and fim gene clusters, what is the function of major pilus subunit gene?

Answer 37

Pilin encoding

Question 38

Intimin 1) 2)

Answer 38

1) 94kDa outer membrane protein | 2) Afimbrial adhesin

Question 39

How does pilin get moved from cytoplasm to cell surface?

Answer 39

1) Sec is a channel which brings pilin from cytoplasm to periplasmic space 2) Pilin needs to form correct disulphide bonds, find chaperone, or else is degraded 3) Chaperone/protein complex binds usher, usher brings pilin from periplasmic space to cell surface. PIlin is incorporated into pilus

Question 40

``` Features of type IV pili 1) 2) 3) 4) ```

Answer 40

1) Don't use usher/chaperone system of transport 2) Usually polar location 3) Can form bundles 4) Play a role in inter-bacterial interactions, host-cell mucosal surface adhesion, twitching motility

Question 41

Relationship between Arp2/3, N-WASP and Nck

Answer 41

Nck joins Arp2/3 and N-WASP to actin

Question 42

What is twitching motility? 1) 2) 3)

Answer 42

1) Different motility to runs and tumbles 2) Bacteria attach, retract pili to move 3) Leading rafts are forwardmost groups of bacteria

Question 43

Which secretion system do type IV pili use?

Answer 43

Type II secretion system

Question 44

Which pili use a type II secretion system?

Answer 44

Type IV pili

Question 45

Is Bordatella pertussis G+ or G-?

Answer 45

Gram -

Question 46

Example of bacterium that uses afimbrial adhesion

Answer 46

B. pertussis

Question 47

Most important afimbrial adhesin in B. pertussis

Answer 47

Filamentous haemagglutinin

Question 48

Features of filamentous haemagglutinin 1) 2)

Answer 48

1) 220kDa protein 2) Contains RGD motif - RGD motif found in human cells, binds fibronectin 3) Most important afimbrial adhesin in B. pertussis

Question 49

Bacteria causing attaching and effacing lesions

Answer 49

EPEC | EHEC

Question 50

Requirements for attaching/effacing lesions

Answer 50

1) Tir | 2) Intimin

Question 51

``` Tir 1) 2) 3) 4) ```

Answer 51

1) Translocated intimin receptor 2) Secreted by bacteria, inserted into host cell membrane 3) Extracellular component binds intimin 4) Intracellular N- and C- termini bind host cytoskeleton

Question 52

Intimin 1) 2)

Answer 52

1) 94kDa outer membrane protein | 2) Afimbrial adhesin

Question 53

Function of Tir intracellular regions

Answer 53

Disrupt normal actin trafficking | Cause accumulation of actin below tir, forms a pedestal for bacterium

Question 54

Tir recruitment of actin is dependent on: 1) 2) 3)

Answer 54

1) Nck 2) N-WASP 3) Arp2/3

Question 55

Relationship between Arp2/3, N-WASP and Nck

Answer 55

Nck joins Arp2/3 and N-WASP to actin

Question 56

Is EHEC virulent without tir and intimin?

Answer 56

No

Question 57

Tir structure

Answer 57

Hairpin loop-like structure

Question 58

Structure of type 3 secretion system

Answer 58

Multiprotein apparatus Proteins span both cell membranes Filmentous structure outside of cell

Question 59

Which bacteria are T3SS found in?

Answer 59

Only in G-

Question 60

EPEC T3SS components

Answer 60

1) ESPA - Filamentous structure | 2) ESPB/D - Insert into host cell membrane

Question 61

What is the function of ESPA?

Answer 61

Filamentous structure of T3SS in EPEC

Question 62

What are ESPB/D?

Answer 62

Parts of EPEC T3SS that insert into host cell membrane

Question 63

What is actin treadmilling?

Answer 63

Polymerisation and depolymerisation of actin

Question 64

What nucleates actin?

Answer 64

Arp2/3 complex

Question 65

``` EPEC binding 1) 2) 3) 4) 5) ```

Answer 65

1) EPEC attaches loosely to host cell with bundle forming pilus (bfp) 2) T3SS inserts tir, intimin is expressed 3) EPEC binds to host cell with high affinity 4) Tir is phosphorylated by host cell kinase 5) Nck is activated. Recruits N-WASP and arp2/3 to polymerise actin