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Biology-9700

Antibodies and Vaccination

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Antibodies and Vaccination

Antibodies


Structure

Antibodies are Y shaped proteins that are made up of four polypeptides. The four peptides consist of two heavy chains and two light chains.

Antibodies consist of two regions a Fab fragment and an Fc region. 

Fab fragment: It is associated with antigen binding.
Fc region: It interacts with the Fc receptor of cells and activates the complement system.

Type Of Antibodies


Polyclonal

During a normal immune response, the antibodies produced are called polyclonal. This is because they are derived from different clones of plasma cells.

Monoclonal

Monoclonal antibodies are homogenous that is they are derived from the same clone. Usually, monoclonal antibodies are produced in a person with multiple myeloma as a plasma keeps dividing.

Production of Monoclonal Antibodies by Hybridoma Method:

Monoclonal antibodies are produced from a single clone of plasma cells and have a homogenous antigen binding site. They can be used in the diagnosis and treatment of different disorders.

Hybridoma Method

It is used to produce monoclonal antibodies.

Principle

The principle of the hybridoma method is to produce a hybrid cell. This cell contains the property of B cell that is the production of antibodies and also the property of myeloma. Due to these myeloma properties, they produce only monoclonal antibodies.

Method

Laboratory animals such as mice are exposed to an antigen. This antigen results in the production of Bells against it. These B cells are extracted and fused with a myeloma cell. Using Electrofusion the B cells and myeloma cells are fused creating a hybrid. This hybrid consists of properties of both cells.

Selection of Hybrid Cells on Hat medium (hypoxanthine aminopterin thymidine medium):

DNA synthesis is essential for cell survival. Aminopterin in the medium blocks DNA synthesis from the de novo pathway. Thus, the cells have to produce nucleotide from the salvage pathway which depends on HGPRT.

Unfused B cells in the medium survive because they have HGPRT. But, their lifespan is short. Unfused myeloma cells do not survive as they do not have HGPRT. Thus the medium will contain only fused cells. 

Use of Monoclonal Antibodies

Monoclonal antibodies are used in the diagnostic kit for various diseases. Once a monoclonal antibody is produced against an antigen it can easily detect it.

Immunity


Definition

The ability of the body to defend itself against a pathogen is called immunity. There are two types of immunity.

Types of immunity


Active immunity


Definition

The immunity that is developed by the body's immune cells.

Natural Active Immunity

That is developed after infection.

Artificial Active Immunity

That is developed after vaccination.

Passive immunity


Definition

The immunity that is provided through preformed antibodies.

Natural Passive Immunity

Antibodies that are transferred through mother to fetus.

Artificial Passive Immunity

Antibodies that are transferred through another person or animal.

Vaccination

Immunization is the process of creating immunity in a person. Vaccination is a method of immunization.

It consists of a dead or weakened pathogen. These pathogens consist of antigens that the immune system identifies and starts an immune reaction against it. Thus, in case of another infection with the pathogen, the body already has antibodies and memory cells. 

Thus vaccination can help in the prevention and control of the disease.

Global Eradication Of Diseases

WHO runs campaigns of vaccination across the world to eradicate diseases. 

Smallpox

Smallpox has been eradicated from the world through vaccination. They have eradicated it successfully by immunizing a large number of people. 

Tuberculosis

Tuberculosis is caused by Mycobacterium tuberculosis. BCG vaccine is developed to provide immunity against. Although WHO is still unable to eradicate it. The reason is that new strains are emerging to due improper antibiotic use among people. 

Measles

Measles have a very high infectious rate thus, a large number of people have to immunized before eradicating it. Besides this, immunity is developed after many doses of vaccine.

Cholera

Cholera is caused by vibrio cholera which causes gastroenteritis. It invades the intestine where it causes the infection. Injectable vaccines are not successful as it takes time to reach the intestines. Oral vaccines are right now under development.

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