Antigens and Immunogenicity Questions and Answers

Q: Which of the following feature(s) should be present in a protein to generate strong immune response (antibody production) in an animal?I. At least one B-cell epitopeII. At least one T-cell epitopeIII. Proteolytic cleavage site(s)

All three features are needed: I, II and III.A strong antibody response to a protein is T-cell dependent. A B cell recognises the protein through a B-cell epitope (I), takes it in and digests it. To do that, the protein must have proteolytic cleavage sites (III) so it can be processed into peptides. One of those peptides must be a T-cell epitope (II), presented on MHC class II to a helper T cell, which then drives the B cell to proliferate, switch class and produce high-affinity antibody.A protein with only a B-cell epitope gives at best a weak response. Any option leaving out one of the three breaks this chain.

Q: If you compare the B cell epitope against T cell epitope :

B cell epitopes are based more on the native conformation of the protein antigen (printed 'nature conformation').Antibodies and B-cell receptors bind intact antigen directly, recognising its three-dimensional surface. Most B cell epitopes are conformational (discontinuous), formed by residues brought together by folding, and they are lost when the protein is denatured.T cell epitopes are the reverse: short linear peptides from the primary sequence, produced by processing and recognised only when presented by MHC molecules. So the options citing primary sequence and MHC presentation describe T cell epitopes, and the last option is garbled.

Q: Mark the correct statement for antigenicity of molecule :

The correct statement is that antigenicity refers to the binding ability of an antibody to its antigen.Antigenicity is the capacity of a molecule to combine specifically with the products of an immune response, antibodies or T-cell receptors. Immunogenicity is the capacity to provoke an immune response in the first place.The two are not synonyms, which makes the first and third options wrong. Every immunogen is antigenic, but not every antigen is immunogenic: a hapten, such as penicillin or dinitrophenol, binds antibody but cannot trigger a response unless coupled to a carrier protein, so 'all antigens are immunogens' is false.

Which of the following feature(s) should be present in a protein to generate strong immune response (antibody production) in an animal?

I. At least one B-cell epitope
II. At least one T-cell epitope
III. Proteolytic cleavage site(s)

A.I only
B.II and III
C.I and III
D.I, II and III

Exam Year(s)

IIT JAM - 2018,

Answer: D

All three features are needed: I, II and III.

A strong antibody response to a protein is T-cell dependent. A B cell recognises the protein through a B-cell epitope (I), takes it in and digests it. To do that, the protein must have proteolytic cleavage sites (III) so it can be processed into peptides. One of those peptides must be a T-cell epitope (II), presented on MHC class II to a helper T cell, which then drives the B cell to proliferate, switch class and produce high-affinity antibody.

A protein with only a B-cell epitope gives at best a weak response. Any option leaving out one of the three breaks this chain.

Discuss in Forum

If you compare the B cell epitope against T cell epitope :

A.B cell epitopes are based more on primary sequence of protein antigen
B.B cell epitopes are based more on nature conformation of protein antigen
C.B cell epitopes are based more on presentation of antigen by MHC molecule
D.B cell epitopes are of continuous epitopes than the B cell epitope

Exam Year(s)

MH SET - 2024, SET Exam - 2024,

Answer: B

B cell epitopes are based more on the native conformation of the protein antigen (printed 'nature conformation').

Antibodies and B-cell receptors bind intact antigen directly, recognising its three-dimensional surface. Most B cell epitopes are conformational (discontinuous), formed by residues brought together by folding, and they are lost when the protein is denatured.

T cell epitopes are the reverse: short linear peptides from the primary sequence, produced by processing and recognised only when presented by MHC molecules. So the options citing primary sequence and MHC presentation describe T cell epitopes, and the last option is garbled.

Discuss in Forum

Mark the correct statement for antigenicity of molecule :

A.Antigenicity is the ability of the molecule to provocate immune response in the body
B.Antigenicity refers to the binding ability of Antibody to its antigen
C.Antigenicity and immunogenicity are synonyms
D.All antigens are immunogens

Exam Year(s)

MH SET - 2024, SET Exam - 2024,

Answer: B

The correct statement is that antigenicity refers to the binding ability of an antibody to its antigen.

Antigenicity is the capacity of a molecule to combine specifically with the products of an immune response, antibodies or T-cell receptors. Immunogenicity is the capacity to provoke an immune response in the first place.

The two are not synonyms, which makes the first and third options wrong. Every immunogen is antigenic, but not every antigen is immunogenic: a hapten, such as penicillin or dinitrophenol, binds antibody but cannot trigger a response unless coupled to a carrier protein, so 'all antigens are immunogens' is false.

Discuss in Forum

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