7.1 Listeria Flashcards
(18 cards)
Listeria monocytogenes associated with what disease
listeriosis
what is listeriosis caused by
food borne infection caused by gram positive bacterium L. monocytogenes
what are disease symptoms of listeriosis
blood infection, meningitis, gut-like disease, inflammation of brain and associated tissue, mother to fetus transmission
three examples of virulence factors in listeriosis
internalin (lnlB), ActA, and LLO
ActA basic description
protein that bacteria produces to help with pathogen’s movement within cells
Binding to host receptors - internalization – what induces internalization
internalin B (lnlB)
internalin B binds to cell surface protein..
Met - tryosine kinase
– Met is normally the receptor for another protein HGP
– pathogen has hijacked normal protein found on membrane and has used it to enter the cell
what type of endocytosis does lnlB use
membrane clathrin mediated endocytosis
what is membrane clathrin mediated endocytosis normally used for
acquiring nutrients and recycling membrane
LLO is an example of an..
exotoxic – secreted from the bacterial cell and serves to form a pore
LLo is tightly regulated by
pH
LLo description
listeriolysin O, pore forming toxin
pore forming steps with LLO
when the bacterium is internalized, it exists in a vacuole, the bacterium cannot replicate in the vacuole, it can only do so in cytoplasm.
- to gain acess to the cyotplasm, LLO will degrade the vacuole membrane forming pores.
- it can do so because of the optimal pH levels (slightly acidic - 6)
- bacterium is then released and can replicate
moving along between cells - journy continues – what kind of pathogen is it
a disseminating patjogen
what does a disseminating pathogen mean
means it can move between different cells
Act A mechanism of action
modulates host cell actin
– allows for actin-based motility using intracellular push
- pathogen is hijacked in actin, and creates a listerio-pod. this gets attached to the host cell actin and gets pushed within the cell leading to eventual intercellular movement
- buds into membrane of host cell and pushes into membrane of neighbouring cell creating a double membrane
actin based motility mediates directed ___ for ewventual ___
intracellular push for eventual intercellular movement
hard for antibiotics to target pathogen because
never leaves compartment of host cell, moves between cell without entering bloodstream where the antibiotics are present therefore evading the defense mechanisms.
