Bacterial Toxins

Question 1

What is one of the most common ways that bacteria prevent phagocytosis and allow for proliferation?

Answer 1

Production and presence of a capsule

Question 2

What are some general properties of bacterial toxins?

Heat tolerance
Immune response
Fever response
Potency
Responsibility for disease

Answer 2

Heat tolerance – heat labile

Immune response – Immunogenic - converted to toxoid by chemical treatment for vaccine

Fever response – MOA doesnt include fever by host

Potency – Toxic at microgram amounts

Responsibility – often entire pathology of pathogen

Question 3

What are the 4 classes of bacterial toxins what do they briefly do?

Answer 3

1. Surface acting - activate signaling receptor on surface
2. Pore-forming - establish new pore for entry portal on surface
3. A/B toxins - phagocytosed and incorporated into synthetic machinery of cell - extremely potent - DpT/BoNT/TeNT
4. Type III and IV secretion - Direct injection/secretion of toxic factors into cytoplasm

Question 4

What is the MOA/Catalytic component, Target, and Effect of Diptheria toxin and *P. Aeruginosa *Exotoxin A?

Answer 4

MOA/Catalytic component - ADP-ribosylation

Target - EF₂

Effect - Inhibits protein synthesis

Question 5

What is the MOA/Catalytic component, Target, and Effect of BoNT and TeNT?

Answer 5

MOA/Catalytic component - Protease

Target - SNARE proteins

Effect - Inhibits release/action of Ach

Question 6

What is the MOA/Catalytic component, Target, and Effect of C diff. toxins?

Answer 6

MOA/Catalytic effect - Glycosylation

Target - Rho proteins

Effect - Diarrhea and Epithelia damage

Question 7

What is the MOA/Catalytic component, Target, and Effect of Shiga toxin?

Answer 7

MOA/Catalytic component - Deadenylation

Target - Adenine on RNA

Effect - Dysentery

Question 8

1. In an A/B organized bacteria, which is the catalytic component?
2. How is an A/B toxin activated?

Answer 8

1. The A portion
2. Through** proteolysis** or disulfide bond reduction

Question 9

Diptheria excretes an intact protoxin. What enzyme splits and activates this A/B toxin?

Answer 9

Trypsin

Question 10

How is Diptheria toxin turned into Diptheria toxoid and used as a vaccine?

Answer 10

It is inactivated by Formalin

Question 11

1. What is a secondary use for diptheria toxoid other than direct vaccination?
2. What is an example of this activity?
3. What type of immune response is created?

Answer 11

1. It is used as a conjugate vaccine carrier
2. Hib polysaccharide vaccines are conjugate vaccines - CRM 197 is a point mutation within DT that inactivates the Hib toxin.
3. T cell dependent immune response (IgM →IgG)