Host Defenses: Antimicrobial Peptides

Question 1

T/F: Penicillin-resistant bacteria were there in the population before they encountered penicillin.

Answer 1

True.

As many mutations are random, not directed, it is possible to have penicillin-resistant bacteria that haven’t been exposed to peniciliin, as shown by the Lederberg Experiment.

Question 2

What percentage of new diseases start in animals?

Answer 2

75%

Question 3

Antimicrobial Peptides

Answer 3

• PMN = polymorphonuclear leukocytes

- Neutrophils

Question 4

How does antimicrobial peptide killing work?

Answer 4

• Defensins break the phospholipids of the microbe.

- This creates a channel into the microbe, which allows H2O in and kills the cell.

Question 5

Three types of Defensins

Answer 5

• alpha
• beta
• theta

Question 6

Cathelicidins

Answer 6

• An antimicrobial polypeptide found in the lysosomes of neutrophils and macrophages
• very diverse
• very species-specific
• NOT defensins!

Question 7

Porcine Cathelicidins

Answer 7

PR-39

PG 1-5

Question 8

Bovine Cathelicidins

Answer 8

Bac-5

Bac-7

Question 9

Human Cathelicidins

Answer 9

LL-37

Question 10

Porcine Beta Defensins

Answer 10

pDB-1

Question 11

Bovine Beta Defensins

Answer 11

TAP
LAP
EBD

Question 12

Human Beta Defensins

Answer 12

hBD 1-4

Question 13

In humans, both defensins and cathelicidins are made by…

Answer 13

neutrophils

Question 14

Host-Defense Peptides

Answer 14

• naturally occuring antibiotics, functional in innate immunity
• protect from invasion by broad range of microorganizms: bacteria, fungi, viruses, and metazoan parasites
• mechanisms of action: pore-forming, LPS-binding, and interference with the microbe’s intracellular metabolism