8.2.3 ACTIVE AND PASSIVE IMMUNITY & 8.2.4 VACCINATION AND IMMUNISATION

8.2.3 Active and Passive Immunity 
  • When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. 
  • This type of immunity is called Active Immunity. 
  • Active immunity is slow and takes time to give its full effective response. 
  • Injecting the microbes deliberately during immunisation (Artificial Active Immunity) or infectious organisms gaining access into body during natural infection induce active immunity (Natural active immunity). 
  • When ready-made antibodies are directly given to protect the body against foreign agents, it is called passive immunity (Artificial passive immunity). 
  • Do you know why mother’s milk is considered very essential for the newborn infant? 
  • The yellowish fluid colostrum secreted by mother during the initial days of lactation has abundant antibodies (IgA) to protect the infant (Natural passive immunity). 
  • The foetus also receives some antibodies (Ig-G) from their mother, through the placenta during pregnancy. 
  • These are some examples of passive immunity. 
8.2.4 Vaccination and Immunisation 
  • The principle of immunisation or vaccination is based on the property of ‘memory’ of the immune system. 
  • In vaccination, a preparation of antigenic proteins of pathogen or inactivated/weakened pathogen (vaccine) are introduced into the body. 
  • The antibodies produced in the body against these antigens would neutralise the pathogenic agents during actual infection. 
  • The vaccines also generate memory – B and T-cells that recognise the pathogen quickly on subsequent exposure and overwhelm the invaders with a massive production of antibodies. 
  • If a person is infected with some deadly microbes to which quick immune response is required as in tetanus, we need to directly inject the preformed antibodies (ATS-Anti Tetanus Serum), or antitoxin (a preparation containing antibodies to the toxin). Anti Diphtheria Serum (ADS) is another example of antitoxin.
  • Even in cases of snakebites, the injection which is given to the patients, contain preformed antibodies against the snake venom. 
  • This type of immunisation is called Artificial passive immunisation. 
  • Recombinant DNA technology has allowed the production of antigenic polypeptides of pathogen in bacteria or yeast. 
  • Vaccines produced using this approach allow large scale production and hence greater availability for immunisation, e.g., hepatitis B vaccine produced from yeast. The MMR vaccine is a vaccine against measles, mumps, and rubella (German measles).
Types of vaccines 
  • First Generation Vaccine: these are whole organism vaccines, either live (Hepatitis B) and weakened (attenuated or killed form- MMR. chicken pox & influenza vaccines)
  • Second Generation Vaccines:  these are sub-unit vaccines, consisting of defined protein antigen (such as Tetanus and Diphtheria Toxoids) or recombinant protein components (Hepatitis B surface antigens produced from yeast and Herpes vaccines)
  • Third Generation Vaccines: These are DNA vaccines, made up of plasmid that has been genetically engineered to produce one or two specific proteins (surface antigen) of pathogen. the recombinant DNA vaccine is then injected into the cells of body, cells produces antigens and body acquires immunity against it. Ex,. Third generation Hepatitis B vaccine.
                 Vaccination Schedule in India, 2016 | PSM Made Easy

  • IPV: Injectable Polio Vaccine
  • HiB: Hemophilus Influenza B Vaccine
  • PCV: Pneumococcal Vaccine
  • BCG: Bacillus Calmette–Guérin vaccine against tuberculosis.
  • OPV: Oral polio Vaccine 
  • HepA: Hepatitis A
  • HepB: Hepatitis B
  • MMR: Measles, Mumps, Rubella Vaccine
  • Varicella: Chicken Pox
  • DPT/DTaP: Diphtheria, Pertussis, Tetanus Vaccine

Think and Answer

  • what kind a polio vaccine is? (active or passive/natural or artificial)

Comments

  1. Subaharitha1 June 2020 at 16:06

    Super.easy to understand.tq sir

    ReplyDelete
    Replies
    1. SKmonuG26 September 2020 at 22:01

      welcome.... let me know if you want me to explain any topic

      Delete

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