micro: exotoxins Flashcards
inactivate elongation factor EF-2
corynebacterium diphtheriae and pseudomonas aeruginosa
corynebacterium diphteriae
diphtheria toxin - inactivates elongation factor EF-2
causes pharyngitis with pseudomembranes in throat and severe lymphadenopathy
pseudomonas aeruginosa
exotoxin A = inactivates elongation factor EF-2
causes host cell death
inactivate 60s ribosome by removing adenine from rRNA
shigella and EHEC (enterohemorrhagic e coli)
shigella
shiga toxin - inactivates 60s ribosome by removing adenine from rRNA
GI mucosal damage causing dysentery and increased cytokine release (HUS)
enterohemorrhagic e coli (EHEC)
shiga-like toxin - inactivates 60s ribosome by removing adenine from rRNA
enhances cytokine release cuasing HUS (0157:H7)
does not invade host cells
increased cAMP causing increased Cl secretion and H2O efflux
heat labile enterotoxigenic Ecoli
increased cGMP causing decreased resorption of NaCl and H2O in gut
heat stable toxin for enterotoxigenic e coli
mimics the adenylate cyclase enzyme causing increased cAMP
edema toxin - bacillus anthracis
increased cAMP by permanently activating G2 causing increased Cl secretion and H2O efflux
cholera toxin of vibrio cholerae (rice-water diarrhea)
increased cAMP by disabling Gi; impairing phagocytosis to permit survival of microbe
pertussis toxin - bordetella pertussis (whopping cough)
proteases that cleave SNARE
clostridium tetani and clostridium botulinum
botulinum toxin
prevents release of stimulatory signals at neuromuscular junctions
tetanospasmin
prevents release of inhibitory (GABA and glycine) neurotransmitters
phospholipase (lecithinase) that degrades tissue and cell membranes
clostridium perfringens alpha toxin
gas gangrene degradation of phospholipids
clostridium perfringens alpha toxin (phospholipase)
protein that degrades cell membranes
streptolysin O of streptococcus pyogenes
stroptococcus pyogenes
streptolysin O degrades cell membrane/lyses RBCs and contributes to beta-hemolysis - host antibodies (ASO) used to diagnose rheumatic fever
binds to MHC II and TCR outside of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN-gamme and TNF-alpha
staphylococcus aureus TSST-1 and streptococcus pyogenes exotoxin A
staphylococcus aureus
toxic shock syndrome causing fever, rash, shock; also has exfoliative toxin causing scalded skin syndrome and enterotoxin causing food poisoning
streptococcus pyogenes superantigen
exotoxin A - toxic shock syndrome of fever, rash, shock
endotoxin effects
lipid A component causes
- macrophage activation (TLR4) (IL-1,6 causing fever; TNF-a causing fever and hypotension; NO hypotension)
- complement activation (C3a causing histamine release, hypotension and edema; C5a casuing neutrophil chemotaxis)
- tissue factor activation (coagulation cascade -> DIC)
