Virulence Factors Flashcards
Protein A
S. aureus
Binds Fc region of IgG, prevents opsonization and phago
IgA Protease (fxn, 3 bugs w/ it)
Cleaves IgA to colonize respiratory tract SHiN Strep pneumo Hib Neisseria
Protein M, what bug, fxn, significance
Strep pyogenes
helps prevent phago
similar epitopes to humans = molecular mimicry
Type III Secretion (what, function, 4 bugs)
Injectisome: needle-like protein that directly injects toxin Gram -'s: Shigella Salmonella E Coli Pseudomonas
Exotoxin
Secreted from cell
Genes located in plasmid/bacteriphage
High toxicity
Induces high-titer ab’s called anti-toxins
Can use toxoid as vaccine
Destroyed rapidily at 60 degree celsius (except staph enterotoxin)
Examples: tetanus, botulinum, diptheria
Endotoxins
Found in most GN’s outer LPS
Generate strong immune response (i.e. sepsis)
Genes in bacterial chromosome
Exotoxin that inhibits EF-2
- Diptheria Toxin* (C. diptheria)
2. Exotoxin A* (Pseudomonas)
Exotoxin that inhibits 60S ribosome by removing adenine from rRNA
- Shiga toxin* (shigella)
2. Shiga-Like-Toxin* (EHEC)
** toxin
AB ribosylating toxin
A: active site, binds ADP-ribosyl and causes damage
B: binding site, binds host for endocytosis
Function of HL* ETEC
activates adenyl cylase → inc cAMP, inc Cl- secretion into gut and H20 efflux
Function of HS ETEC
activates guanylate cycle → inc cGMP, dec NaCl absorption and increase H20 efflux
Edema Toxin*
Bacillus anthracis
Mimics adenylate cycle anzyme, inc cAMP
permanantly activates Gs receptor, inc cAMP
Cholera toxin*
“rice water stools”
activates cAMP by inhibiting Gi (bug and result)
Pertussis Toxin* (bordatella pertussis)
-inhibits phagocytois, and allows for survival
proteases that cleave SNARE proteins (required for NT release via vesicular fusion) - 2
- Tetanospasmin*: inhibit GABA and Glycine release from Renshaw cells in spinal cord
- Botulinum*: inhibit Ach release at NMJ
Alpha Toxin * (bug, function, s/s)
C. perfringens
Toxin is a phospholipase (lecithinase) that degrades tissues and cell membranes
Break down PLs: myonecrosis + gas gangrene
Hemolysis: double zone of hemolysis on blood agar
Streptolysin O (bug, fxn, s/s)
Strep pyogenes
Lyses RBCs, contributes to beta-hemolysis
Can use anti-SO (ASO) ab’s to dx RF
Superantigen function
Binds MHC and TCR at site other than antigen binding site. Cause huge release of cytokines:
IL-1, IL-2, IFN-alpha, IFN-gamma → shock
S aureus superantigens (3)
TSST-1 (toxic shock: fever, rash, shock)
Exfoliative toxin: scaled skin
Enterotoxin: food poisoning
S pyogenes superantigen
Exotoxin A: fever, shock, rash
don’t confuse w/ pseudomonas Exotoxin A* - blocks protein synthesis
5 toxins w/ gene transfer via speciallized, lysosomal phages
ABCDE
- shigA-like toxin: SLT* (EHEC)
- Botulinum* (certain strains)
- Cholera toxin*
- Diptheria toxin*
- Erythrogenic toxin - i.e. S pyogenes Exotoxin A
dipicolonic acid in the core
spore stage, can form at the end of stationary phase when nutrients are limited.
no metabolic activity
whats required to kill spores
autoclave at 121 degrees celsius for 15 min
3 species with spore forms
Bacillus
Clostridium
Coxiella burnetti (Q fever)
