ingegral bacterial membrane components that are released upon cell lysis
What are 3 examples of endotoxins?
(1) lipopolysaccharide (LPS)
(2) Lipoteichoic acid (LTA)
(3) phosphatidylgylcerol (PG)
gram-NEGATIVE cell wall
gram-POSITIVE cell wall
BACTERIAL cell membrane
What do macrophages produce after bacteria release endotoxin
IL-1, released in bloodstream to brain where induce fever
polyketide-derived; cytotoxic and immunosuppressive properties
produced by Mycobacterium ulcerans, causative agent of Buruli ulcers (emerging disease), responsible for necrotic skin lesions- little inflammation and painless
proteins secreted by b bacteria (usually enzymes) that alter the normal metabolism of host cells, with subsequent deleterious effects on the animal, at exquisitely low levels
Do all pathogenic bacteria produce exotoxins?
NO, but CAN be produced by BOTH gram (+) and (-) bacteria
Exotoxins are MOST often secreted by bacteria into _______
surrounding milieu =
"effector proteins" or "exoenzymes"
specialized secretion systems that deliver exotoxin by direct injection into host cell cytoplasm
What are the 3 types of A-B toxins?
(1) diptheria toxin - single chain
(2) cholera toxin- multi-subunit
(3) anthrax toxin- multi-subunit (bigger)
(phage) SINGLE chain A-B toxin encoded by bacteriophage; internalized via receptor-mediated endocytosis; ADP-ribosylation of EF-2
(chromosomal) multisubunit; ADP-ribosylation of G protein; increases cellular cAMP
(plasmid) multi-subunit (bigger than cholera) w/ 2 catalytic subunits and 7 "B' subunits
What are the 2 catalytic subunits of Anthrax toxin?
(1) Edema factor- adenyl cyclase
(2) lethal factor- An-dependent protease
what are the 7 "B" subunits of anthrax toxin called?
protective antigen (PA83)
What toxin has heparin-binding epidermal growth factor on heart and nerve surfaces?
shigella, E.coli- inhibits protein synthesis
(v. cholerae) chromosomal; activation of adenylatecyclase, increase cAMP level, secretory diarrhea
What are the 4 exotoxin classifications?
(1) A-B toxins
3 types of proteolytic toxins?
(1) tetanus neurotoxin (tetanospasmin)
(2) botulinum neurotoxin
(3) elastase and protease
(Costridium tetani) proteolytic clevage of synaptobrevins (CNS) --> SPASTIC PARALYSIS
(clostridium botulinum) proteolytic cleavage of synaptobrevins (peripheral NS) --> FLACCID PARALYSIS
elastase and protease IV (proteolytic toxin)
(pseudomonas aeruginosa) breakdown of cellular matrix
what neurotoxin causes SPASTIC PARALYSIS?
what neurotoxin causes FLACCID paralysis?
gram (+), obligate anaerobe, small amts. cause disease, PREFORMED exotoxin, only toxin NOT bacteria needs to enter host
How does botulinum neurotoxin enter host?
ingestion of contaminated food, multiply in stomach, absorbed through intestinal wall - site of action in neuromuscular junction
membrane disrupting toxins in gram NEGATIVE bacteria
RTX toxins (repeat present in each toxin); have different target host specificities, share a conserved secretion mechanism (Type 1)
EXAMPLE membrane disrupting toxins in gram NEGATIVE bacteria
E. coli hemolysin (HlyA)
membrane disrupting toxins in gram POSITIVE bacteria
EXAMPLE membrane disrupting toxins in gram POSITIVE bacteria
listeriolysin O from Listeria monocytogenes
IgA protease-type protein toxin
gram (-), encode their own secretory secretion (AUTOTRANSPORTERS), share a conserved secretion mechanism (Type 1)
encode their own secretory secretion
bind to MHC clss II cells and T cells outside Ag-binding grove & cause intense IR due to release of cytokines from host cells
classic ex. of superantigen
toxic shock syndrome toxin (TSST) of staphyloccus aereus