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19 Cards in this Set
- Front
- Back
understand the concept of host pathogen relationship
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commensalism-mutual, no effect on host.
colonisation, persistance, disease becomes parasitic relationship; detrimental to host, beneficial to parasite. both host and pathogen have evolved mechanisms to evade eachother's responses |
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list the major defence mechanisms that limit extracellular infection
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phagocytosis
opsonising antibodies antibody complement mast cells and eosinophils cross linking IgE |
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how do extracellular pathogens evade the immune system?
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molecular mimicry
avoid phagocytosis by restricting phagocyte chemotaxis ie pertussis toxin inhibit binding of Fc portion ie Staphyloccocus A protein produce toxin to kill phagocytes capsule/biofilm polysaccharide coat resists opsonisation |
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where do intracellular pathogens hide in the cell?
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cytosol or phagosomes
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why are Th1 CD4+T-cells so important in attacking intracellular infection?
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Because Th1 cells secrete IFN gamma which activates macrophages. macrophages are crucial for fighting intracellular infection.
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why are CD8+T-cells important in fighting some intracellular infections?
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MHC class 1 molecules present endogenous proteins i.e. viruses, bacteria etc to CD8+T-cells, CD8+ T-cells therefore are needed to recognise some endogenous cytosolic antigens
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how do macrophages kill intracellular pathogens?
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by reactive nitrous oxide and oxygen species.
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list functions of IFN gamma
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-primes production of reactive N and O2 species
- forces phagolysome formation -increases MHC class I and II expression -induces iron deprivation and acidification of phagolysome. -increases costimulatory molecules |
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which two cells secrete IFN gamma
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NK cells
Th1 cells |
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outline the lifecycle of a virus and the mechanisms of the host immune system to counteract these events
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1. virus attachs to cell, antiodies and complement try to prevent this
2. virus enters cell cytosol 3. viruses begin to replicate inside host cell, IFNs interfere with replication by recognition of PAMPS i.e dsRNA 4. viruses eventually leave cell to infect new cells, dendritic cells attempt to catch them, NK cells limit immune evasion by secreting IFN gamma, granzymes, perforin etc. CD8+T-cells induce apoptosis in virally infected cells |
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what public health measures apart from vaccination increase overall health in a society
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clean water
good hygiene practices antibiotics vector control (insects, rodents) safe sewage disposal avoid overcrowding |
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what are the aims of immunisation?
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protection of individual and community
prevention of serious disease and death containment of disease outbreak elimination of specific diseases |
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explain toxoid vaccines
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used to immunise against bacterial disease the vaccine contains antitoxins that lead to development of inactivated toxin a toxoid. toxoid vaccines are safer but induce a weaker immune response and require multiple doses
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what type of antibodies is the recipient of a toxoid vacccine generating?
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neutralising antibodies i.e IgG
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what were the first two live vaccines for humans?
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rabies and tuberculosis
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explain the initiation of in vitro vaccine culture
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in 1931 it was discovered that a fertile hen's egg could be used as a culture for vaccine production. a cheaper and safer alternative.
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what is EPI?
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Expanded Program on Immunisation launched by WHO Aim was to achieve maximum disease control with high levels of immunization coverage with greatest number of countries
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describe hypersensitivity reaction types
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type I- allergic reaction, Th2, IgE mast cells eosinophils
type II- cytotoxic antibody dependent IgM IgG type III- immune antigen-antibody complex IgM IgG type IV- delayed type hypersensitiviy- Th1- IL-2, IFN gamma = macrophages, CD8+T-cells |
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which diseases are covered by EPI?
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tuberculosis
DTP (diptheria,tetanus pertussis) polio measles |