FINAL Flashcards
Which QS molecule is used by Gram Positive? where are they sensed?
AIP, AI-2
TCS, sensed outside
Which QS molecule is used by Gram Negative? where are they sensed?
AI-2, AHK, AI-1
inside the cytoplasm because they are membrane diffusable
Endotoxin
part of the bacterial pathogen, further characterized by their mode of action
- LPS, LTA/TA, peptidoglycan, PAMPs
- weakly antigenic, highly immunogenic (PAMPs)
Exotoxin
secreted into the surrounding - types 1,2,3
Type 1 and examples
binds to the target cell surface and acts extracellularly (ex.:
superantigen)
Type 2 and examples
Type II toxin: binds to target cell surface and acts on the eukaryotic cell membranes (pore-forming toxins, phospholipases)
Type 3 and examples:
AB type toxin; binds to the target cell surface, enters the host cells and activates or inactivates intracellular targets.
when are endotoxins released?
replication or when the cell lyse
4 clinical stages of septic shock
- Systemic inflammatory response syndrome (SIRS): fever or hypothermia, high heart rate and high
respiratory rate. - Sepsis: SIRS + documented septicemia (presence of bacteria in the blood stream).
- Severe sepsis: organ dysfunction and low blood pressure. At this stage 70% of patients will die.
- Septic shock: low blood pressure despite administration of fluid.
Exotoxin example : nonprotein
mycolactone
lipid - good at crossing membranes
-cytotoxic effect, causing necrotization of host cells and has an immunosupressive property
-lesions
-intracellular pathogen, grows in macrophages, and necrotic tissue
Exotoxin example: protein
TSST-1
cuase massive activation of T cells and macrophage, massive release of cytokines and causes cytokine storm - shock
exotoxin types and roles : type 2 protein
- kill host cell
- destroy phagosome and enter the cytoplasm
- exit the cell
phosophoilpases - PlcA, PlcB in L. monocytogenes destroy the phagosome membrane
pore forming toxins - cause an inrush of water and therefore cell lysis
Explain entry of AB toxins into the cell
- B subunit binds
- phagosome formation
- travels to the Golgi
- high influx of H+
- disulfide bridge broken
- A subunit released into the cytoplasm to find target
Diphteria toxin
- causes damage to the mucosa of the throat - forms pseudomembrane
- Entry: decrease in PH causes a conformational change in B to a pore and A is exposed to the cytoplasm. Reducing conditions reduce the disulfide bond and the A subunit is freed into the cytoplasm to find the target.
- A subunit : ADP-ribosylation of host cell proteins
- causes inactivation or change in activity of the protein
- targets: EF-2: stops protein elongation, G protein: ion disruption, water flows out of the cell
- antitoxin(purified antibodies against DT) are good vaccines against the disease
what are the targets of the anthrax toxin?
andenylate cyclase, zinc dependent protease - leads to cleavage of MAPK - lethality?
AB7 type toxin
A subunites are called EF and LF
