L7 virulence factors and phagocyte interactions

Endotoxins are QS controlled

True

What type of toxin acts by lysing host cells and attacking cell constituents?

Cytolytic toxins

A

B toxins consist of which two subunits?

What do superantigens overstimulate in the host?

T cells

What percentage of T cells do superantigens activate compared to normal antigens?

5

Which cytokine is overproduced first by T cells under superantigen stimulation?

IFN

Which cytokines do macrophages overproduce after IFN

gamma stimulation?

Name a bacterial example producing superantigens.

Staphylococcus aureus

What disease is associated with Staphylococcus aureus superantigen TSST

1?

Which foods are commonly contaminated with superantigen toxins?

Tinned meat, fish, contaminated dairy

What is the last

resort antibiotic for resistant Staphylococcus aureus?

Intoxication refers to what kind of toxin exposure?

Uptake of preformed toxin

Colonisation with in situ toxin production requires what bacterial condition?

High

Which bacteria produce A

B enterotoxins in situ?

Which bacteria produce cytotoxins in situ?

Clostridium perfringens

Siderophores are used by bacteria to acquire which element?

Iron

Which host proteins tightly bind iron to restrict bacterial access?

Hemoglobin, transferrin, lactoferrin

Low iron concentration triggers synthesis of what bacterial molecules?

Siderophores

Corynebacterium diphtheriae toxin expression is controlled by what environmental factor?

Iron availability

What phage encodes the diphtheria tox gene?

Beta phage

What protein represses diphtheria toxin expression?

DtxR

Defensive virulence factor that prevents phagocytosis?

Capsule

Enzyme that degrades IgA to avoid opsonisation?

IgA protease

Enzyme that neutralises reactive oxygen species?

Superoxide dismutase

Phagocytosis is dependent on which cellular component?

Actin

What type of particle size can phagocytes ingest?

0.5 µm or larger

Opsonic phagocytosis requires coating of the prey with what?

Immunoglobulins

Non

opsonic phagocytosis relies on recognition of what?

Name two PAMPs recognized by phagocytes.

Adhesins, LPS O

What are the main receptors on immune phagocytes?

Toll

What are the main receptors on amoebae for non

opsonic phagocytosis?

Mechanism that allows bacteria to survive phagosome shock by producing chaperones?

Tolerance

Which sigma factor is involved in stress protein upregulation?

σ^32 (o32)

Which chaperones are involved in bacterial stress response?

DnaK and DnaJ

What process allows bacteria to survive by inhibiting lysosomal fusion?

Avoidance

Which enzyme protects bacteria from host ROS in phagosomes?

Superoxide dismutase

Bacteria that divide within phagosomes of amoebae and humans?

Legionella pneumophila

Type IV secretion system used by Legionella pneumophila?

Dot/Icm

Bacteria that escape the phagosome and replicate in cytoplasm?

Salmonella typhimurium and Listeria spp.

What is the result of cytoplasmic replication of bacteria?

Increased virulence and resistance