Lecture 12: Bacteria and Disease 2 Flashcards
what does ID stand for?
Infectious Dose
what is ID 50?
the dose which infects 50% of individuals
what is immunity?
the ability of an organism to resist infection
what is innate immunity?
- non-specific
- immediate response
- no immunological memory
what are the primary effector cells in innate immunity?
phagocytes
what is adaptive immunity?
- specific to an antigen
- lag time from exposure to response
- immunological memory
what are the primary effector cells in adaptive immunity?
lymphocytes
what are phagocytes?
cells that engulf foreign particles
what are PAMPs?
Pathogen Associated Molecular Patterns
what is the role of PAMPs?
get recognised but Pattern Recognition Receptors to distinguish cells as pathogens
what does Toll like Receptor 2 recognise?
peptidoglycan from gram positive bacteria
what does Toll like receptor 4 recognise?
Lipopolysaccharides from gram negative bacteria
what do phagocytes produce once the bacteria is engulfed and why?
chemokines to recruit other immune cells to the site of infection
what 4 ways may a pathogen avoid phagocytosis?
- bacterial capsule preventing PAMPS
- inhibit phagosome and lysosome function
- neutralise phagolysosome
- produce toxins that kills phagocytes
what can intracellular pathogens also be destroyed by?
Natural Killer Cells
what do B cells do?
specialise in the production of antibodies
what do T cells do?
express antigen specific receptors defending against pathogens
what is specificity?
the antigen being a specific protein associated with a single strain of virus
what is memory (in terms of antigens)?
clones recognising specific antigens after infection
which region of the antibody binds to the antigen?
variable region
what does the constant region of an antibody do?
interacts with immune cells
what are the 4 roles of antibodies?
- bind to and neutralise pathogens
- bind to toxins and virulence factors to block action
- enhance phagocytosis
- induce cytokines
what are the 3 antibody classes that have to constant regions?
IgG, IgA and IgD
what are the 2 antibody classes that have 3 constant regions?
IgM and IgE
what is 5 antibodies together called?
(IgM) pentamer boned with a J chain
what is 2 antibodies joined together called?
(IgA) dimer bonded with a J chain
what are the 3 steps of primary response?
- initial antigen contact
- IgM antibody production
- without the antigen antibody production decreases
what are the 3 steps of secondary response?
- another contact with the same antigen
- antibody class switches to IgG
- titer decreases as antigen decreases
when do septic and toxic shock occur?
when infection spreads to the blood stream
what does septic and toxic shock cause?
uncontrolled systemic inflammation
what is septic and toxic shock induced by?
lipopolysaccharides from gram negative bacteria entering the blood
what is toxic shock induced by?
superantigen exotoxins
