Listeria Monocytogenes

Question 1

What are the main virulence factors?

Answer 1

Biofilms and out competition

Question 2

How does Listeria enter the epithelial cell?

Answer 2

Internalin A/B bind to Ecad and Met for endocytosis –> vacuole –> Listeriolysin LLO and phospholipases plcA/plcB rupture vacuole which leads to changes in the host cell
Actin is polymerized to spread laterally
–> mito morphology, ER stress, permeability

Question 3

How does Listeria replicate in Macrophages?

Answer 3

in SLAPs (Spacious listeria containnig phagosomes)

Question 4

What creates the virulence factors?

Answer 4

prfA promoter- vacuole escape and intracellular invasion (LnlA, LnlB, Act, LLO, plcA, plcB)
20C weakly active
37C- positive feedback where cofactors bind to it

Question 5

What are the 3 barriers that it penetrates>

Answer 5

intestinal
blood/brain
placental

Question 6

What happens in the liver?

Answer 6

Kupffer cells phagocytise Lm cells - Necroptosis (programmed cell death)
Calls monocytes to carry into blood/brain barrier

Question 7

What is Listeria sensitive to?

Answer 7

killed with pasteurization,
10% salt
pH 4.4

Question 8

Persistant versus reoccurring?

Answer 8

Persistant is the same strain
Reoccruing is different strains

same virulence factors (doesnt change much)

Question 9

What happens in goblet cells? MAcrophages? Trophpblasts?

Answer 9

Line mucosal surfaces
inLa binds to E-cadherin → uptake in cell
Lm remains internalised in vacuole and transcytosis through cell

MAcrophages
Phagocytizes into SLAPs,Lm can replicate
LLO interferes with concentration gradient → acidification no rupture

Trophoblasts
Placenta epithelium
inLB binds Met → phosphorylation → endocytosis

Question 10

What interactions does Lm have?

Answer 10

microbiota → lm produce bacteriocin (listeriolysin (LLS) that restricts growth of common commensal bacteria
Immune→ IgA secreted into mucus layer

Question 11

What happens from the surface level with Lm?

Answer 11

After ingestion,Lm encounters the intestinal epithelium, traverses the barrier to the lamina propria and then disseminated via the lymph and blood towards the target organs (liver and spleen)
In the blood, Lm is carried to the liver
In the liver Kupffer cells phagocytosis Lm cells and then succumb to necroptosis (programmed cell death)

Question 12

Explain the gene regulation of Lm.

Answer 12

Below 37 there is no translation due to loop

Above 37C the cofactor can bind and this leads to production fo Lm

Question 13

What is a way that Lm causes disbiosis?

Answer 13

LLO restricts growth of natural microbes