36 terms

virulence, exotoxins, endotoxin

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virulence factors function to
promote evasion of host immune response
Staphylococcus aureus - virulence factor?
Protein A
Staphylococcus aureus - virulence factor function?
binds Fc region of Ig to prevent opsonization and phagocytosis
Streptococcus pneumoniae - virulence factor?
IgA protease (cleaves IgA in order to colonize respiratory mucosa)
Haemophilus influenzae type B - virulence factor?
IgA protease (cleaves IgA in order to colonize respiratory mucosa)
Neisseria - virulence factor?
IgA protease (cleaves IgA in order to colonize respiratory mucosa)
mnemonic for bacteria which secrete IgA protease
SHiN (S. pneumoniae, H. influenzae type B, Neisseria)
Group A streptococcus (Streptococcus pyogenes) - virulence factor?
M protein
Group A streptococcus (Streptococcus pyogenes) - virulence factor function?
prevent phagocytosis
exotoxin characteristics
polypeptide secreted from cells, encoded on plasmids/bacteriophages, induces antitoxins, not very heat stable
endotoxin characteristics
lipopolysaccharide on outer cell membrane of most Gram negative bacteria, encoded on bacterial chromosome, induces TNF and IL-1 (fever and shock), poorly antigenic, heat stable
Corynebacterium diphetheriae - exotoxin function?
inactivates elongation factor (EF-2) via ADP-ribosylation
Pseudomonas aeruginosa - exotoxin function?
inactivates elongation factor (EF-2) via ADP-ribosylation
Shigella - exotoxin function?
inactivates 60S ribosome by cleaving rRNA
Enterohemorrhagic E. coli (EHEC) - exotoxin function?
inactivates 60S ribosome by cleaving rRNA
Enterotoxigenic E. coli heat-labile - exotoxin function?
overactivates adenylate cyclase --> increases cAMP --> increases Cl- secretion in gut and H20 efflux
Enterotoxigenic E. coli heat-stable - exotoxin function?
overactivates guanylate cyclase --> increases cGMP --> decreases reabsorption of NaCl and H20 in gut
Yersinisa enterocolitica - exotoxin function?
overactivates guanylate cyclase --> increases cGMP --> decreases reabsorption of NaCl and H20 in gut
Bacillus anthracis - exotoxin function?
mimics adenylate cyclase enzyme --> increases cAMP
Vibrio cholerae - exotoxin function?
overactivates adenylate cyclase by permanently activating Gs --> increases cAMP --> increases Cl- secretion in gut and H20 efflux
Bordetella pertussis - exotoxin function?
overactivates adenylate cyclase by inactivating Gi --> increases cAMP --> impairs phagocytosis to permit microbe survival
Clostridium tetani - exotoxin function?
cleaves SNARE protein required for (inhibitory - GABA and glycine) neurotransmitter release
Clostridium botulinum - exotoxin function?
cleaves SNARE protein required for (stimulatory - ACh) neurotransmitter release
Clostridium perfringens - exotoxin function?
phospholipase (lecithinase) which degrades tissue, cell membranes --> myonecrosis and hemolysis
Streptococcus pyogenes - exotoxin?
Streptolysin O
Clostridium perfringens - exotoxin?
Alpha toxin
Streptococcus pyogenes - exotoxin function?
lyses RBCs, contributes to beta-hemolysis
Streptococcus pyogenes - superantigen?
Exotoxin A
Streptococcus pyogenes - superantigen function?
brings MHC II and TCR in proximity to cause overwhelming release of IFN-gamma and IL-2 --> shock
Staphylococcus aureus - superantigen function?
brings MHC II and TCR in proximity to cause overwhelming release of IFN-gamma and IL-2 --> shock
Staphylococcus aureus - superantigen?
TSST-1
exfoliative toxin causes
scalded skin syndrome
enterotoxin causes
food poisoning
Bacillus anthracis - exotoxin?
Edema factor
Pseudomonas aeruginosa - exotoxin?
Exotoxin A
endotoxin activates
macrophages, alternative complement pathway, Hageman factor (XII)