Unit 8.1: Antimicrobial Substances

What are the four Antimicrobial substances?

1. The complement system

2. Interferons

3. Iron-binding proteins

4. Antimicrobial peptides

What is Cytolysis?

Cytolysis is when complement proteins form a membrane attack complex (MAC) which creates holes in the pathogens membrane

Which specific bacteria can evade Cytolysis / MAC

1. Gram positive bacteria

2. Bacterial capsules

3. Some gram-negative bacteria

4. Some gram negative and positive bacteria can release an enzyme that breaks down C5a

Complement system - Cytolysis Process

What is opsonization?

Opsonization is when a pathogen is coated with C3b proteins or antibodies, making them more identifiable

Complement system - Opsonization process

Complement system - Inflammation process

What are the two types of Interferons?

1. Gamma interferon

2. Alpha and beta interferon

What is Gamma interferon’s function?

Gamma interferons activate immune cells

What are Alpha and beta interferon’s functions?

• Signals neighboring cells to destroy RNA and reduce protein synthesis

• Signals neighboring infected cells to undergo apoptosis

What are the four proteins in the human body that bind to iron and their locations?

1. Lactoferrin: in tears

2. Transferrin: blood and tissue fluids

3. Ferritin: liver, red bone barrow

4. Hemoglobin: red blood cells

What do Antimicrobial peptides do?

Antimicrobial peptides kill bacteria, viruses, and fungi

What are the Antimicrobial peptides’ modes of action?

Modes of action: form pores in plasma membrane, inhibit cell wall synthesis, destroy DNA/RNA

What are some examples of Antimicrobial peptides?

1. Defensins

2. Dermcidin

3. Bacteriocin