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���������������� ��Unit 1: Nature of the Immune System ��Part 1: Introduction and Historical Concepts�

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Introduction

  • Immunology is a relatively new field
  • Entire history recorded in the last 100 years
  • 1960s cells of immune system identified and characterized
  • Tests developed to detect presence of immune substances in the blood

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What You Need To Know

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Immunity

  • Immunology defined as the study of the reaction of a host when foreign substances are introduced into the body
  • Antigen is the substance recognized as foreign to the body which causes an immune response
  • Immunity is the condition of being resistant to infection
  • Serology is the study of the non-cellular components (serum) in the blood

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Immunization/Vaccination

  • Purposeful exposure of individual to infectious material to elicit immunity
  • Early forms of vaccination were developed in ancient China as early as 200 B.C.
  • People inhaled powdered scabs from people infected with smallpox to protect against the disease

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Vaccination – Edward Jenner

  • Smallpox affected all levels of society
  • Jenner noticed that milkmaids did not generally get smallpox
  • Jenner theorized that the pus in the blisters which milkmaids received from cowpox (a disease similar to smallpox, but much less virulent) protected the milkmaids from smallpox

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Vaccination – Edward Jenner

  • Inoculated 8-year-old with material from pus in cowpox blisters
  • Exposed boy to infectious agents and no disease followed
  • Jenner's unique contribution was not that he inoculated a few persons with cowpox, but that he then proved they were immune to smallpox
  • Process called vaccination, from vacca, Latin for cow

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Ethical Smallpox Issue

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“Last Samples of Smallpox Pose a Quandary”�

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Vaccination

  • A vaccine - biological preparation that elicits immunity to a particular disease
  • A vaccine may be:
    • Weakened forms of pathogens
    • Killed or inactivated forms of pathogens
    • Purified material such as proteins which are similar to pathogens
  • Stimulates the body's immune system to recognize the agent (antigen) as foreign, destroy it, and "remember" it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters

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Vaccination - Types

  • Killed microorganisms
  • Attenuated – live organisms cultivated to disable virulent properties (MMR, yellow fever vaccines)
  • Toxoid – inactivated toxic compounds in cases where these (rather than the micro-organism itself) cause illness (ex: tetanus/diptheria)
  • Subunit – fragments create an immune response
  • Conjugate – linking outer coats to proteins which can the lead immune system to recognize it-(Haemophilus influenzae type B)
  • mRNA - vaccine uses a copy of a messenger RNA to produce an immune response. (Covid vaccine)

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Rabies

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Rabies

  • A viral disease that causes acute encephalitis (inflammation of the brain).
  • It is zoometric (i.e., transmitted by animals), most commonly by a bite from an infected animal but occasionally by other forms of contact
  • The period between infection and the first flu-like symptoms is normally two to twelve weeks, but can be as long as two years
  • Rabies is almost invariably fatal if post-exposure prophylaxis is not administered prior to the onset of severe symptoms

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Rabies

  • Louis Pasteur applied the principle of attenuation to a rabies vaccine
  • Developed a rabies virus that was milder and had a shorter incubation period than the wild virus
  • A person bitten by a rabid animal would be inoculated with the Pasteur virus and rapidly develop immunity to the wild strain�

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Rabies

  • He developed his rabies vaccine by growing the virus in rabbits, then drying the affected nerve tissue (spinal cords) to weaken the virus
  • On July 6, 1885, the vaccine was administered to a 9-year-old boy who had been attacked by a rabid dog
  • The boy survived and avoided contracting rabies, which would have almost certainly proved fatal
  • http://www.historylearningsite.co.uk/louis_pasteur.htm