VL9: Bacterial adhesion

Question 1

Name some of the 12 S steps of a successful pathogen

Answer 1

sex (acquire virulence gene)
sense (the environment)
switch (virulence genes on and off)
swim (to the site of infection)
stick (to the side of infection) ADHESION
scavenge (nutriens, iron)
survive (stress)
stealth (avoid the immune system)
strike (damage host tissues)
subvert (host cell cytoskeleton and signalling pathways)spread (through cells and organs)
scatter (transmit to other organisms or environments)

Question 2

Why is adhesion important?

Answer 2

-initial interaction to host cells to colonize a site
-avoid clearance by mucosal secretion and peristalsis
mediate signaling events important for bacterial uptake or invasion
-promote anti-inflammatory events by affecting innate immune receptors e.g. evading complement deposition

Question 3

To what can bacteria adhere?

Answer 3

-epithelial layer
endothelial layer (line interior surface of blood/lymphatic vessels)
-mucosa
-extracellular matrix-blood

Question 4

What surface structures of e.coli are involved in adhesion?

Answer 4

some that lack specific target: capsule, LPS, flagella, cellulose

Question 5

Name major bacterial adhesion families (5, gram- and2 gram+)

Answer 5

uhjk

Question 6

Describe chaperone-usher pili

Answer 6

type 1 pili and p-pili

type 1 pili: fimH adhesin (responsible for hemagglutination in acute kidney infections

p-pili papG adhesin: part of papthogenicity island

important for UTI:
fimH mediates brinding to mannosylated receptors -> important for UPEC colonization and invasion
type 1 pili are required for survival

effective vaccine againstfimH

Question 7

Type 4 pili

Answer 7

expressed by all gram negatives, and some gram positives
-flexible filament with thousands of repeating pilin subunits

1. play structural roles in motility and biofilm formation -> twitching motility
2. role in dna binding and uptake
3. roel in adhesion to host cells and host cell signalin -> induces internalization of neisseria
4. possible role in communication of electrical signals as nanowires

Question 8

What do curli fibers do?

Answer 8

• adhesion to surfaces
• bacterial aggregation
• biofilm formation
• host cell adhesion and invasion
• induce host inflammatoru response

Question 9

why do bacteria use lipid raft for entry?

Answer 9

to avoid phagosome fusionm
-triggering of cell signaling that leads to membrane ruffling and rearrangement of the cytoskeletion reqyuired for entry of bacteria

generate vacuoles (with raft assocaiated receptors) that have a defined intracellular trafficking pathway
hijack raft associated signalling pathways

Question 10

actin rearrangement

Answer 10

bacterial adhesion often causes actin rearrangements

• promotes bacterial uptake
• and bacterial movement in the cell

Question 11

complement

Answer 11

complement regulators are sometimes used as bacterial adhesin receptors
bacteria can escape recognition by complement system through the actions of cellsuface or secreted proteins that interfere with complement activation