Virulence factors are pathogen-produced extracellular enzymes or structural components of pathogens that aid in the colonization, multiplication, invasion, and evasion of host immune response.
Enzymes which acts as virulence factors
- Hyaluronidase: It promotes the spreading of the organisms in tissues by breaking down hyaluronic acid.
- Collagenase: It breaks down the collagen network supporting the tissues.
- Streptokinase: It is a fibrinolytic enzyme. Fibrin clots trap the microorganisms and limit their spread.
- Coagulase: It is a fibrin clotting enzyme and helps the organism to localize in a particular site, e.g., wounds.
- Hemolysins: Breakdown of RBCs.
- Lecithinases (or phospholipases): Help the organism to break down phospholipid-lecithin.
- Leukocidins: Kills white blood cells.
Toxins
Toxins such as diphtheria toxin, cholera toxin, botulinum toxin, toxic shock syndrome toxin, tetanus toxin, botulinum toxin, etc., aids in the pathogenesis of respective pathogens.
Surface components
- Capsule: Antiphagocytic
- Lipopolysaccharide layer: Endotoxin
- Teichoic acid: Endotoxin, etc.
You can get detailed information on the virulence factors of each pathogen with their functions in the below-mentioned blog posts.
