102. Short Chain variable fragments (ScFv) of antibody are composed of :
A. 𝑉𝐻 and 𝑉𝐿 domains with 𝐶𝐻 domain
B. 𝑉𝐻 and 𝑉𝐿 domains along with Fc region
C. 𝑉𝐻 and 𝑉𝐿 domains
D. Only Complementarity Determining Regions

Detailed Explanation:

Short Chain Variable Fragments (ScFv) are engineered antibody fragments used in various biotechnological and therapeutic applications, such as targeted therapy and diagnostic imaging. They are the result of combining the variable regions of both the heavy (VH) and light (VL) chains of an antibody into a single chain. This design allows the ScFv to retain its antigen-binding specificity while being much smaller than full-length antibodies.

Composition of ScFv:

• VH domain: The variable heavy domain of the antibody contributes to one part of the antigen-binding site.

• VL domain: The variable light domain pairs with the VH domain to form the other part of the antigen-binding site.

Unlike full antibodies, ScFvs do not contain the constant regions (such as the CH domain or the Fc region). The Fc region is responsible for binding to Fc receptors and mediating immune responses, but it is not present in ScFv fragments.

Answer Breakdown:

• A. VH and VL domains with CH domain: Incorrect. ScFvs do not include the CH domain, which is present in full antibodies.

• B. VH and VL domains along with Fc region: Incorrect. The Fc region is absent in ScFvs.

• C. VH and VL domains: Correct. ScFvs are composed of the variable heavy (VH) and variable light (VL) domains, linked together in a single polypeptide chain.

• D. Only Complementarity Determining Regions: Incorrect. While CDRs (complementarity determining regions) are critical for antigen-binding specificity, ScFvs are made from the entire VH and VL domains, not just the CDRs.

Correct Answer:

C. VH and VL domains