Module 2: Section 2D

Question 1

Innate immune system

Answer 1

• Nonspecific, first defense
• Quickly attacks foreign invaders

Question 2

Adaptive immune system

Answer 2

• Specific, slower response.
• Uses specialized immune cells to target and remember pathogens

Question 3

Host immune response to bacterial structures

Answer 3

If innate immunity is bypassed, adaptive immunity activates antibodies that target bacterial surface structures.

Question 4

Why do surface structures trigger antibodies

Answer 4

• Structures like flagella, pili, and S-layers have 100s–1000s of identical proteins
• Makes them highly visible to the immune system

Question 5

How does Salmonella reach the intestinal wall to replicate?

Answer 5

It uses flagella to swim through the intestine and penetrate the wall

Question 6

What is the most antigenic protein on Salmonella flagella?

Answer 6

• FliC protein
• found in thousands of copies per flagellum

Question 7

How does Salmonella evade host antibodies targeting FliC?

Answer 7

It switches off FliC and produces FljB instead

Question 8

Where are LPS and LTA found?

Answer 8

• LPS = Gram-negative bacteria
• LTA = Gram-positive bacteria

Question 9

What effects do LPS/LTA cause?

Answer 9

• Highly immunogenic and trigger strong immune responses
• Fever, blood pressure changes, decreased heart function

Question 10

How do LPS/LTA trigger effects?

Answer 10

• Start with endotoxins interacting with TLRs on the surface of immune cells (called monocytes)
• Series of complex steps

Question 11

What do monocytes release when activated?

Answer 11

Cytokines that trigger inflammation and tissue damage

Question 12

How does tissue damage help bacteria?

Answer 12

Tissue damage releases nutrients and lets bacteria invade deeper tissues