Convince the expert bacterial escape

Question 1

What does TLR 3 recognise?

Answer 1

ds RNA in de endosome

Question 2

What does TLR 7 recognise?

Answer 2

ssRNA in the endosome

Question 3

What does TLR 8 recognise?

Answer 3

ss RNA in de endosome

Question 4

What does TLR 9 recognise?

Answer 4

CpG DNA, intracellular bacteria and viruses

Question 5

What does TLR 5 recognise?

Answer 5

flagellated bacteria

Question 6

What does TLR 2 recognise?

Answer 6

bacterial peptidoglycan

Question 7

What does TLR4 recognise

Answer 7

LPS

Question 8

What are the 4 postulates of Koch?

Answer 8

1. micobe must be present in disease but absent in healthy organisms
2. suspected microbe must be isolated and grown in pure culture
3. result in same diseasee when isolated
4. microbe must be isolated again and be identical to original specific causative agent

Question 9

What is meant by: tolerance by exclusion?

Answer 9

is to ensure that inflammatory response is only directed at pathogens and not commensals. The host reduces interactions with its normal microbiota with different cell layers. Pathogens will want to invade and then come in contact with the leukocytes. commensals do not do this, thus will not activate the inflammatory response.

Question 10

What is meant by: tolerance by constraint?

Answer 10

Commensal microbes can inhibit pro-inflammatory reactions. this is done by either inducing the export of NF-kB with PPAR-Y or inhibiting the ubiquitination of IkB

Question 11

What receptors will be activated in order to initiate phagocytosis?

Answer 11

• scavenger
• FcY receptors
• complement receptors
• mannose receptors
• PRR

Question 12

what are the 3 main effector mechanisms of the complement system?

Answer 12

• amplification
• opsonisation for phagocytosis
• membrane attack complex

Question 13

What is the C3 convertase?

Answer 13

C4b2a

Question 14

What is the c5 convertase?

Answer 14

C4b2a3b

Question 15

What c wil form the attack complex?

Answer 15

C5b, c6,7,8 and 9 will form the attack complex of the complement system

Question 16

What pathway can discriminate between microbial cells and the human cells?

Answer 16

The alternative pathway, it detects markers on host cells and activates on anythingthat lacks similar markers.

Question 17

How can bacterial pathogens evade phagocytosis?

Answer 17

• inhibition of phagolysosome fusion
• resistance to lysosomal enzymes
• adaptation to cytoplasmic replication

Question 18

How can bacterial pathogens prevent the effects of the antibody?

Answer 18

• block the immune system recognition (inhibiting C3)
• inhibit immune system activation by inhibition cytokines
• induction of phagocytee apoptosis
• antimicrobial peptides

Question 19

What pathogen can use the M-cell to invade the host?

Answer 19

pseudotuberculosis, it uses invasin to go through the M-cell into the PP by interacting wht B1 integrin.

Question 20

How do cholerae, perfringens and lamblia disrupt mucus and tight barrier function?

Answer 20

Cholerae secretes HAP, it has a mucolytic activity, interacts with occludin(in tight junction).
Lamblia reorganises the filaments and disrupts the ZO1 to increase permeability of the epithelium
Perfringens focuses on the claudin (mainly 3 and ) proteins of the tight junctions.

Question 21

Why does the monocytogene use goblet cells as entry?

Answer 21

becausee the E-cadherin receptors are easier to access by the pathogen. (moment when the goblet is empty)

Question 22

How can S. typhmurium escape the effect of the Paneeth cells?

Answer 22

Paneth cells secrete defensin. Typhmurium can change the charge of surface molecule lipid A in paneth cells(more positive). this will inhibit the releasee of defensin

Question 23

How do salmonella and shigella overcome exlusion?

Answer 23

salmonella: invade in the M-cells and enterocytes and replicate there. Use a T3SS to inject toxins in host cells

Shigella: invade the lining of colonn. they enter macrophages and epithelialcells by secreting four proteins, they replicate in cytoplasm. they can travel to adjecent cell

Question 24

How do salmonella and shigella evade the immun system?

Answer 24

salmonella: PAI II evade the hosts immune response. they can induce the apoptosis of macrophages and induce inflammation by secretion of IL-1B

Shigella: also induces apoptosis of macrophages.

Question 25

Why can S. aureus and pyogenes be so dangerous

Answer 25

Both can secrete a toxin that overactive the immune system, a superantigen. there are specific binding sites where we are highly susceptible for them. This can result in toxic shock syndromes