Defence and vaccination against infection Flashcards
What is active immunisation?
Achieved via vaccination which induces host immune response of B and T cells
What is passive immunisation?
Injection of pre-formed immunological mediators such as the gamma-globulin antibodies. These are IgA, IgM and IgG.
What is passive immunisation a treatment for?
Hypogammaglobuniemia: low levels of antibodies
Maternal antibodies
Tetanus, gangrene, snake bite, HepB
What is an essential feature of the adaptive immune response?
Clonal expansion of T lymphocytes
What are effector mechanisms of natural protection?
Lysis of infected target cell by T cells with antigen
Release of lymhpokines which mediate macrophages and other WBC
Antibody synthesis
What are the types of vaccines?
Live vaccines and non-living vaccines
What are the live vaccines?
Weakened form of pathogen by reducing its virulence. This can be natural or artificial.
There is a risk it may revert to the form capable of causing disease via mutation. Can be ingested and single dose.
What are the benefits of live vaccines?
Live attenuated vaccines can replicate and generate an identical response to natural infection and the natural immunity acquired.
However, the protection reduces over time so re-immunisation is important.
Cheaper than inactivated vaccines.
What is the immune response for live vaccine?
IgA, igG and IgM antibodies.
What are the artificial vaccines?
Adminstered via injection and requires adjuvant to stimulate the immune system, mediated by IgG only. It has a high cost
What are examples of viral infections treated by artificial vaccines?
Measles, mumps, rubella, rabies, Hep A, polio and yellow fever
What are examples of bacterial infections treated by artificial vaccines?
Salmonella, vibrio cholerae, bordatella pertussi and e.coli
What is the treatment for smallpox vaccine?
Live vaccine which uses cowpox, a weaker strain similar enough to grant immunisation without causing severe disease.
Artificial vaccine.
What are non-living vaccines formed of?
This is achieved by growing pathogen in a culture and using heat or chemicals to inactive it. Includes:
Antigenic parts of a pathogen
Killed whole pathogen
DNA/RNA from pathogen
What is a subunit vaccine?
Non-living vaccine which contains a portion of the pathogen to trigger immunogenicity.
Typically, it is most effective when used with an adjuvant, a substance that can be pathogenic or non-pathogenic like aluminium to cause a heightened immune response.
What is an example of a subunit vaccine?
DTP: diptheria, tetanus and pertussis. Contains tetanus toxin and bordatella that acts as adjuvant for toxins.
What is diptheria?
Severe bacterial infection which targets the upper airways and causes sore throat, difficulty breathing and death.
Caused by corynebacterium diphtheria, a gram positive bacilli.
What is tetanus?
Bacterial infection by clostridium tetani produce tetanus toxin which binds to post synaptic receptor and inhibits neurotransmitter signals from renshaw cells for inhibition of movement. Causes stiffness and leads to difficulty breathing. Toxin is used as a carrier in the subunit vaccine DTP for immunogenicity.