Question

Antibody response to a protein vaccine can only be obtained

• A. If the peptide bonds are maintained
• B. If the peptide bonds are not maintained
• C. If the molecule is glycosylated
• D. If the molecule is first linked to a carrier

Hint:

Protein vaccines must be stored within a strict temperature range (cold chain) to prevent denaturation and hydrolysis of peptide bonds, which would destroy the epitopes needed to stimulate immunity.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Protein vaccines contain purified proteins or peptide fragments from pathogens that act as antigens to stimulate a protective antibody response.
For an antigen to stimulate B-cells to produce specific antibodies, it must preserve its structural epitopes.

Step 2: Detailed Explanation:
The primary structure of a protein is defined by its amino acid sequence, which is held together by covalent peptide bonds.
This primary sequence determines how the protein folds into its secondary, tertiary, and quaternary structures.
The structural sites recognized by antibodies are called epitopes.
These can be classified into two types:
Linear (sequential) epitopes, which are formed by a continuous sequence of amino acids.
Conformational (discontinuous) epitopes, which are formed by amino acids brought together by the folding of the polypeptide chain.
If the peptide bonds of a protein vaccine are cleaved (for example, by enzymatic hydrolysis, heat damage, or chemical breakdown), the primary structure is destroyed.
This cleavage breaks the linear sequence of amino acids and unfolds the protein, destroying both linear and conformational epitopes.
Without these intact epitopes, the antigen cannot bind to B-cell receptors (BCRs) or be processed and presented on MHC Class II molecules to helper T-cells.
As a result, the immune system cannot generate a specific antibody response.
Therefore, maintaining the integrity of the peptide bonds is essential to preserve the structural epitopes required to stimulate an antibody response.

Step 3: Final Answer:
An antibody response to a protein vaccine requires that the peptide bonds are maintained.