EXAM 4 Immune System Failure: Pathogen Evasion and Immunodeficiency Flashcards
what are the 5 classes of immunodeficiency?
- humoral immunity
- cellular immunity
- combined
- phagocytic cells
- complement
describe the humoral immunity class of primary immunodeficiency
- makes up 60% of primary immunodeficiencies
- reduced or absent serum immunoglobulin
- impaired B cells
- selective IgA deficiency is the most common
describe the cellular immunity class of primary immunodeficiency
- makes up 10% of primary immunodeficiencies
- impaired T cells
- predisposition to viral, fungal, and opportunistic pathogens
- most common - DiGeorge syndrome, ZAP-70 deficiency, x-linked lymphoproliferative syndrome, chronic mucocutaneous candidiasis
describe the combined class of primary immunodeficiency
- makes up 20% of primary immunodeficiencies
- deficiencies in both B cell and T cell function (ex. knocking out RAG proteins)
- severe combined immunodeficiencies
describe the phagocytic cell class of primary immunodeficiency
- makes up 10% of primary immunodeficiencies
- impaired phagocytosis
- frequent gram neg infections
- most common - chronic granulomatous disease, leukocyte adhesion deficiency, chediak-higashi syndrome
describe the complement class of primary immunodeficiency
- very rare (<2% of primary immunodeficiencies)
- deficiencies in complement components, inhibitors, or their production
- recurrent bacterial infection
- autoimmune disorders
in what ways can pathogens evade the immune system?
- serotype diversity
- antigenic drift
- antigenic shift
- gene conversion
- latency
- *evasion = avoiding the immune system*
in what ways can pathogens subvert the immune system?
- endocytic hijacking
- protein mimicry
- humoral inhibition
- inflammation inhibition
- immunosuppression
- superantigens
- *commandeering the immune system* aka take control of the immune system and use it for the pathogens on benefit
describe serotype diversity
- type of pathogen evasion
- high genetic variability
- not necessarily highly mutable
- useful for tracking outbreaks
- ex:
- person infected with one serotype of s. pneumoniae
- antibody response clears infection
- antibodies cannot prevent infection with a second serotype of s. pneumoniae
- new antibody response clears second infection
a ___ is an antigenically different strain of the same pathogen
serotype
___ describes mutations in the viral genome driven by selective pressure as the virus infects a population
antigenic drift
describe antigenic drift as a pathogen evasion mechanism
- viral genomes are highly mutable
- tied to memory erosion
- responsible for viral epidemics (regional)
___ describes genetic recombination that leads to significant change in viral antigens
antigenic shift
antigenic shift is responsible for viral ___
pandemics (worldwide)
describe gene conversion as a pathogen evasion mechanism
- trypanosomes (a parasite) change cell surface glycoprotein expression
- VSG gene rearrangement
- one VSG dominant at any time
- minority express other VSGs
- humoral evasion
- population cycling with VSG expression
- VSG = variable surface glycoprotein
describe endocytic hijacking as a subversion mechanism
- utilize endocytosis for cellular entry
- prevent lysosome fusion
- escape phagosomes
- survive autolysosomal environment
describe superantigens as a subversion mechanism
- potent toxins that disrupt immune function
- gram positive bacteria
- s. aureus and s. pyogenes
- non-specific T cell activation
- antibody and complement inactivation
describe the immune response to HIV over time
