Pathogenesis Flashcards
innate immunity is ____ and ____
quick and nonspecific
Innate immunity is ____ and ____
quick and nonspecific
Innate immune cells are…
phagocytes (neutrophils and macrophages)
Adaptive immune cells are…
T and B cells
Adaptive immunity is ____ and ____
slow and specific
Which cells make antibodies?
B cells
What is a pathogenicity island?
a section of bacterial chromosome that differs from the surrounding “ocean” of DNA sequences as a result of horizontal genetic exchange
Type 3 bacterial secretion system = ?
a virulence factor! can inject into host cells
How can one pathogen cause different diseases?
All pathogens have a core genome in common within their species, but the addition of variable elements (like phage DNA or plasmids) can introduce new virulence factors and accessory machinery
Role of pili in adherence?
different pili have different subunits (tip of tail) that bind to different receptors
What is facultative adherence?
some pathogens can have both extracellular and intracellular means of adherence/invasion depending on conditions/host
Advantages of intracellular lifestyle?
protection from extracellular immune response, protection from abx, “trojan horse” transportation, get host nutrients from cytoplasm
Disadvantages of intracellular lifestyle?
exposed to intracellular defenses, spatial limits on growth, limited to one host/harder to transmit to new host, inflammatory damage when host cell is damaged
How do enveloped viruses attach to host cell receptors?
via envelope glycoproteins
Do nonenveloped viruses have glycoproteins?
No!
HA on flu virus binds ___ on respiratory epithelial cells
sialic acid
GP120 (glycoprotein) on HIV binds ___ on host immune cells
CD4
How do nonenveloped viruses attach to host cell receptors?
via capsid components, i.e. spike structures
How do spikes on nonenveloped viruses confer diversity?
Difference in spikes –> different serotypes that bind to different receptors and determines what tissue infected
What is the purpose of antigenic variation?
swap out surface antigens periodically to evade host immune responses launched against them by the host
Antigenic variation vs serotypes
AV: short time scale, rapid evolution within life of a single organism or population
S: much longer time scale!
How can some capsules evade the human immune system?
By being too similar to human polysaccharide antigens for immune system to distinguish between self and pathogen
What are the functions of the A and B subunits of exotoxin?
A = enzymatic activity B = binding
Difference between alpha, beta, and gamma hemolysis?
alpha = partial hemolysis beta = complete hemolysis gamma = no hemolysis
An example of a pore-forming exotoxin is ?
hemolysin
Exotoxin vs endotoxin - secreted from cell?
Exo: yes, actively from viable microbes
Endo: no, part of bacterial architecture
Exotoxin vs endotoxin - chemical makeup?
Exo: polypeptide
Endo: lipopolysaccharide
Exotoxin vs endotoxin - relative toxicity?
Exo: very toxic
Endo: variable toxicity
Exotoxin vs endotoxin - relative antigenicity?
Exo: very antigenic (triggers immune response easily)
Endo: poorly antigenic
What is meant by an “exfoliative toxin?”
Literally skin peels, i.e. scalded skin syndrome
5 main ways pathogens can avoid clearance by immune system:
- protective polysaccharide coat
- attaching to host cells/tissues
- invading host cells
- latency
- changing antigenic characteristics
Main role of pili?
adherence
Main role of capsule?
anti-phagocytosis mechanism
Main role of toxins?
inflict cell and tissue damage
