Lecture 12: Immune Invasion Flashcards
5 immune evasion strategies by bacteria
- Evasion of antimicrobial peptides
- Impairment of tracheal clearance
- Adhesion and penetration of epithelial barriers
- Evasion of phagocytosis
- Evasion of complement killing
Antimicrobial peptides
A family of peptides with bacterial activity
Example of bacterial peptides
Beta-defensins forming inactive complexes
Two bacteria that use evasion of antimicrobial peptides
- Staph aureus: Uses staphylokinase to bind beta-defensins to form inactive complexes
- Bordetella bronchiseptica: Uses an unidentified virulence factor, reduces beta-defensing reproduction by sequestering NF-KB
Three bacteria that use impairment of tracheal clearance
- Psued. aeruginosa: Mutliple toxins to slow or stop ciliary beating
- Borde. pertussis: Tracheal toxin - induces production of NO within epithelial cells, impairing their ability to clear mucus
- Mycoplasma: Induce derangement of cilial function
5 ways to prevent activation
- Activate masking substances
- Apply appropriate inhibitors of activation to surface
- Cover up target of membrane attack complex
- Inactivate complement chemotaxin C5a
- Activate surface of plasminogen to plasmin and cleave C3b
Two ways to activate masking substances and the bacteria that do them
- Staph: Coat with capsule
2. Meningococci: Coat with IgA antibodies
Three ways to apply appropriate inhibitors of activation to surface and the bacteria that do them
- E.coli, Borrelia, and Group B strep: Bind factor H
- Schistosome: Bind decay-accelerating factors
- Vaccinia virus: mimic components
What bacteria cover up the target of membrane attack complex?
E.coli
Salmonella
What bacteria inactivate complement chemotaxin C5a
Group A strep
Pseudo. aeruginosa
What bacteria activate surface plasminogen to plasmin to cleave C3b
Staph aureus
What two bacteria induce apoptosis/lysis of lymphocytes
- Bacillus anthracis: produce lethal toxin and edema toxins
2. Salmon. enterica
