Synthetic oligopeptide vaccines, Advantages & Disadvantages

 Synthetic oligopeptide vaccines

 

By the term itself, Synthetic oligopeptide vaccines refers to the vaccines that are synthetically prepared from protein or peptides containing  amino acids. However, the peptides may vary in its no. of amino acids. Here, we will deal simply about synthetic peptide vaccines.

Concept:

After using vaccines from microorganisms (Viral, Bacterial) for a long time in the past which was difficult and also somehow dangerous approach,  people felt the need of easy way of vaccination. It comes from the concept of subunit vaccines, which uses reductional approach instead of using large molecules. Microorganisms  can be dangerous as they can undergo reversion to convert themselves into pathogen, so why not use only parts of them identifying their antigenic site instead of using the whole organism? so that they can’t replicate by their own. It means, they will be safer to use as vaccines..

So smaller regions of fragments or peptides of the large molecules that can mimic the antigenic sites of proteins, so that protective immunity can be elicited against disease. Example, FMD, HBV, Influenza, cholera, COVID, etc.

 

Introduction:

They are subunit  vaccines made from peptide(amino acid) of pathogens. They are also called epitope vaccines, as the peptide mimics the epitope of the antigenic site that triggers immune response. Antigenic epitope is not a simple sequence of amino acids, but composed of various parts of the protein sequence building 3D structure.

 

When are they used?

-When there’s no availability of natural antigen and in adequate amounts.

-When natural antigens are unstable.

-When pathogen is dangerous.

-For easier and safer approach.

 

Advantages:

-As they are synthetic, there is no risk of mutation or reversion so that there is no risk of contamination by pathogenic or toxic substances.

-They are highly specific biochemical tools and are precisely defined.

- They are more stable , easier and safer materials for vaccination.

-This vaccines is free from unnecessary components  from undesired part of organism, so there’s no side effect.

-It is said that it exposes the parts of the antigen not seen by immune system during natural infection.

 

Disadvantages:

-The approach outlined is not without practical and theoretical difficulties.

-The choice of epitope to synthesize is restricted to linear epitopes.

- Antibodies are unable to find and bind the folded structure of target proteins. Hence, Antibodies raised against peptides in this case can fail to work on immunoassays.

-Maybe costly and difficult to identify and purify proteins.

- Requires highly effective adjuvants or delivery vehicles(as rapidly dissipated in tissues.)