Bacterial Pathogenesis (Exam 1) Flashcards
_______ is secreted by living bacteria with a specific activity against hos tissues.
exotoxin
_______ is inside a bacterial cell envelope and is released when it disintegrates or dies.
endotoxin
What are “superantigens”?
surface-acting exotoxins
Superantigens bypass normal antigen presentation binding _______ to stimulate _______.
MHC
T cells
Superantigens stimulate T cells which produces what major effect?
cytokine storm (excess IL-2 production)
(T/F) Superantigens have an effect at a systemic but not a local level.
False - can be either
Locally, superantigen effects are _______, while systemically, they lead to _______.
flesh-eating
toxic shock
A-B exotoxins have A which is the ______ subunit and B which is the ______ subunit.
active
binding
Direct, “door-to-door” delivery of toxins from a bacterial cytoplasm to a eukaryotic host uses what system?
Type III secretion system
_______ is reversible variation while ________ is irreversible variation in terms of rearrangements of major surface protein genes in bacteria.
phase variation
mutation
Term for small molecule secreted by pathogens which binds a host’s iron for import into bacteria.
siderophores
Lethal pathogens have a (low/high) LD50 and ID50.
low
LD50s are (higher/lower) than ID50s.
higher
Term for adherence factors of bacteria which help them stick to host ligands.
adhesins
What is an example of an adhesin on bacteria?
fimriae/pili
Term for molecule which help bacteria into a host cell.
invasins
Term for molecule on bacteria that binds to a host receptor which allows bacteria to internalize into a host cell after a signaling cascade occurs.
internalin
What is the name of the mechanism bacteria use to internalize into a host cell using internalin?
zipper mechanism
List the 2 strategies pathogens use to evade a host’s immune system.
- form capsules, S-layers, biofilms
- antigen/phase variation
Antigenic variation is a strategy used by pathogens to evade a host’s immune system which leads to (low/high) frequency mutations in (specific/random) genes.
high
specific
Term for bacteria that can replicate both inside and outside a host cell.
facultative intracellular
Term for bacteria that cannot replicate outside a host cell.
obligate intracellular
(T/F) All intracellular bacteria replicate within the host cytoplasm.
False - cytoplasm or vacuoles
List 4 ways a host defends itself against intracellular pathogens.
- ROS
- antimicrobial peptides
- apoptosis
- lysozyme
What mechanism do intracellular pathogens use to evade host defenses which contain virulence factors for protection?
pathogenicity islands
Two molecules hosts make that bind iron and prevent pathogens from acquiring it.
lactoferrin
transferrin
Two membrane disrupting proteins pathogens have which can cause tissue damage to the host.
hemolysin
leukotoxin
Hemolysin is a pore-forming toxin of _______ while leukotoxin is a pore-forming toxin of ______.
RBCs
WBCs
