Damage by microbial toxins Flashcards
What are the 3 mechanisms that damage the host during infections?
Cell death
Damaged caused by host responses
Alteration of the metabolism of host cells by toxins
______ of host cells occurs via growth of pathogen within host cells, cell-mediated immunity, and membrane-damaging toxins
Lysis of host cells
________ damage causes cell death (free radical-induced lipid peroxidation).
Cell membrane
Damage caused by host responses via ________ due to exaggerated adaptive immune response = hypersensitivities
Uncontrolled inflammation
______
–healthy response-increased blood supply (redness)
-increased vascular permeability (edema)
-chemotaxis (infiltration by phagocytes and lymphocytes)
Inflammation
______ hypersensitivity = allergy but can lead to anaphylaxis and shock
Type I hypersensitivity
______ hypersensitivity = bound antibodies leading to complement and leukocyte activation to surfaces
Type II hypersensitivity
______ hypersensitivity = bound antibodies leading to complement and leukocyte activation to soluble molecules, then immune complex deposition (e.gin glomeruli)
Type III hypersensitivity
______ hypersensitivity = inflammation by purely CMI responses (not antibodies)
Type IV hypersensitivity
What Ig and type of cell is seen in Type 1 hypersensitivity?
Mast cell and IgE
Microbial product or component that can injure another cell or organism at low concentrations
Toxins
What are the 3 ways toxins act?
Modulation of targets inside a host cell
Action in the extracellular matrix
Action on surface of a host cell
T/F: Toxin production and disease consequences vary widely among pathogenic bacteria
True
T/F: Like transposons, many toxin-encoding genes are carried on plasmids or temperate bacteriophage genomes (easy to transfer to other, non-toxigenic bacteria).
True
Once in a host that is integrated in via bacteriophage genome integrated in V. cholerae genome: ____ and _____ encode the proteins that comprise cholera toxin
ctxA and ctxB
______ -secreted by pathogens that Modulate targets inside a host cell
Exotoxins
_______ -injected into host cells contact-dependent Modulate targets inside a host cell
Type III cytotoxins
______ are secreted by Type I or II secretion systems
Exotoxins
What are the 3 common features of exotoxins?
- A-B toxins (2 components)
- Require activation (proteolysis or reduction of disulfides)
- Many are ADP-ribosyltransferases
Which domain of exotoxins _______ is the binding domain?
B domain
Which domain of exotoxins _______ is the enzymatic “active” domain?
A domain
_____ domain of exotoxins also mediates the entry of the _____ domain into the host cell
B domain; A domain
What compound in the action of diphtheria toxin inhibits translocation reaction of protein synthesis?
ADP-Ribosyl-EF-2
_______ include collagenases, hyaluronidases, DNases , streptokinase (Streptococcus pyogenes) activates plasminogen (converts to plasmin) and help microbes spread
Exoenzymes
Protection against exotoxins A. Immunization with _____
toxoids
Protection against exotoxins B. Treatment with ______passive immunization
antitoxins
