Anergy,active and passive immunity ,vaccination | Immunology | first aid lectures | Lec21 #drjamil
Channel: Dr. Jamil Lectures
Date: 07/04/2022

In this lecture we will discuss about anergy,active and passive immunity and vaccination.vaccination types like live attenuated vaccine,illed or inactivated vaccine,subunit,toxoid vaccines


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Anergy
State during which a cell cannot become activated by exposure to its antigen. T and B cells become anergic when exposed to their antigen without costimulatory signal (signal 2). Another mechanism of self-tolerance.
Passive immunity
Receiving preformed antibodies Exposure and is rapid in action.
 DURATION
Short span of antibodies (half-life = 3 weeks)
EXAMPLES
 IgA in breast milk, maternal IgG crossing placenta, antitoxin, humanized monoclonal antibody
NOTES
 After exposure to Tetanus toxin, Botulinum 
toxin, HBV, Varicella, Rabies virus, or 
Diphtheria toxin, unvaccinated patients are 
given preformed antibodies (passive)
Active immunity
exposure to exogenous antigen and is slow in its action.
Long lasting protection along with memory.
examples are  natural infection ,vaccines and toxoid.
Combined passive and active immunity can be given to HBV and rabies patient.
Vaccination
 Induces an active immune response (humoral and/or cellular) to specific pathogen
Live attenuated vaccine
Microorganism loses its pathogenicity but retains capacity for transient 
growth within inoculated host. Induces cellular and humoral responses. MMR and varicella vaccines can be given to HIV ⊕ patients without evidence of immunity if CD4 cell count ≥ 200 cells/mm3
.Pros: induces strong, often lifelong immunity.
Cons: may revert to virulent form. Often contraindicated in pregnancy and 
immunodeficiency.
Examples
Adenovirus (nonattenuated, given to military recruits), Typhoid (Ty21a, oral), Polio (Sabin), Varicella (chickenpox), Smallpox, BCG, Yellow fever, Influenza (intranasal), MMR, Rotavirus
Killed or inactivated vaccine
Pathogen is inactivated by heat or chemicals. Maintaining epitope structure on surface antigens is important for immune response. Mainly induces a humoral response.
Pros: safer than live vaccines.
Cons: weaker immune response; booster shots usually required.
Examples
Hepatitis A, Typhoid (Vi polysaccharide, intramuscular), Rabies, Influenza, Polio (SalK)
Subunit vaccine
Includes only the antigens that best stimulate the immune system.
Pros: lower chance of adverse reactions.
Cons: expensive, weaker immune response.
Examples
HBV (antigen = HBsAg), HPV (types 6, 11, 16, and 18), acellular pertussis (aP), Neisseria meningitidis(various strains), Streptococcus 
pneumoniae, Haemophilus influenzae type b.
Toxoid vaccine
Denatured bacterial toxin with an intact receptor binding site. Stimulates the immune system to make antibodies without potential for causing disease.
Pros: protects against the bacterial toxins.
Cons: antitoxin levels decrease with time, may require a 
booster.
Examples
Clostridium tetani, Corynebacterium diphtheria

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