Immunization Immunizing Agents Immunoprophylaxis And Immunotherapy
Question 1. Write notes on live attenuated vaccines.
Or
Write briefly on live attenuated vaccines.
Answer:
Live attenuated vaccines provide active immunization.
- A single dosage of live vaccine is sufficient for providing immunization.
- Attenuated organism in body multiplies and provide continuous antigenic stimulus and serves both as primary and booster dosage.
- Attenuated organisms are suspensions of living organisms whose virulence is reduced.
- Live attenuated vaccines mimic natural infection with antibody production without symptoms. In these level of immunity induced is same as natural infection and the immunity last for several years.
- Live attenuated vaccines can be administered by route of natural infection and parenterally.
- Some examples of live attenuated vaccines are Sabin vaccine for poliomyelitis, Ty21a for typhoid, BCG for tuberculosis, MMR vaccine for measles, mumps, rubella and 17D vaccine for yellow fever.
- For preparation of live vaccines, sometimes antigens of related organisms should be taken, example Bovine tubercle bacillus for BCG vaccine.
- Live attenuated vaccines should be not given in immunocompromised states.
Read And Learn More: Microbiology Question And Answers
- Attenuated strains for live vaccines have following criteria:
- Should not be non-virulent.
- Should be able to set up intestinal infection and should induce an immune response.
- Should not acquire neurovirulence after serial enteric passage.
- Should posses stable genetic markers by which they can be diffrentiated from wild virulent strains.
Live Attenuated Vaccines Advantages:
- Single dose is sufficient.
- Administered through route of natural infection for inducing local immunity.
- It provides both humoral and cell mediated immunity
- Immunity provided is longer and effective.
Live Attenuated Vaccines Disadvantages:
- Can lead to local and remote complications.
- Presence of risk of reversion of virulence in immunocompromised individuals.
- Live organism can spread from vaccine to contacts
Leave a Reply