Immunity to bacteria

Question 1

What are the four main mechanisms of antibacterial immunity?

Answer 1

Antibody production, phagocytosis, antimicrobial peptide AMP production, and coordination of adaptive immunity

Question 2

What role do antibodies play in bacterial immunity?

Answer 2

They neutralize bacterial toxins, opsonize bacteria for phagocytosis, and activate the complement system

Question 3

What is NETosis?

Answer 3

A process where neutrophils release their DNA and antimicrobial proteins to trap and kill bacteria

Question 4

How do antimicrobial peptides AMPs contribute to immunity?

Answer 4

AMPs disrupt bacterial membranes and inhibit bacterial growth

Question 5

What is the role of reactive oxygen species ROS and nitric oxide NO in immunity?

Answer 5

They are produced by phagocytes to kill bacteria during the respiratory burst

Question 6

How do pneumococci evade phagocytosis?

Answer 6

They have a thick polysaccharide capsule that blocks complement binding

Question 7

Why is antibody production critical for combating pneumococcal infections?

Answer 7

Pneumococci must be opsonized with antibodies for effective phagocytosis

Question 8

What is the role of pneumolysin in Streptococcus pneumoniae infections?

Answer 8

Pneumolysin is a toxin that damages host cells and promotes inflammation

Question 9

What are the primary sites of Streptococcus pneumoniae infections?

Answer 9

Nasopharynx (carriage), lungs (pneumonia), blood (sepsis), and meninges (meningitis)

Question 10

How do bacterial pathogens modulate the host immune response?

Answer 10

By secreting toxins, modifying surface antigens, and inhibiting complement and phagocytosis

Question 11

What is antigenic hypervariability?

Answer 11

Frequent changes in bacterial surface antigens to evade immune detection

Question 12

What is the significance of IgA proteases in bacterial infections?

Answer 12

They degrade IgA, weakening mucosal immunity and allowing bacterial invasion

Question 13

What are bacterial superantigens?

Answer 13

Molecules that non-specifically activate T cells, leading to massive cytokine release and immune dysregulation

Question 14

How do bacteria block phagolysosome fusion?

Answer 14

By producing factors that inhibit the maturation of phagosomes, allowing bacterial survival in host cells

Question 15

What are examples of Gram-positive bacterial pathogens?

Answer 15

Staphylococcus aureus, Streptococcus pneumoniae, and Clostridium difficile

Question 16

What are examples of Gram-negative bacterial pathogens?

Answer 16

Escherichia coli, Salmonella, and Pseudomonas aeruginosa

Question 17

How does bacterial LPS contribute to septic shock?

Answer 17

LPS activates TLR4, triggering excessive inflammation and systemic cytokine release

Question 18

What are bacterial strategies to inhibit complement activation?

Answer 18

Production of proteases, surface capsules, and long-chain LPS to evade complement-mediated killing

Question 19

What is the role of T regulatory cells in bacterial immunity?

Answer 19

Tregs help control excessive inflammation and prevent tissue damage during bacterial infections

Question 20

What is the effect of pollution and inhaled sand on bacterial infections?

Answer 20

They increase bacterial carriage and virulence, reduce Treg activity, and promote inflammation

Question 21

How does pneumococcal vaccination work?

Answer 21

Vaccines like PCV-13 induce antibody responses to prevent invasive disease and reduce nasopharyngeal carriage

Question 22

What is the leading bacterial pathogen causing deaths in children under 5 years old?

Answer 22

Streptococcus pneumoniae, a leading vaccine-preventable cause of death

Question 23

How does the immune system balance inflammation and bacterial clearance?

Answer 23

By regulating pro-inflammatory cytokines with anti-inflammatory cytokines like IL-10

Question 24

What are the effects of pneumolysin on the immune response?

Answer 24

Pneumolysin depletes complement, activates the inflammasome, and reduces neutrophil killing