Question

1a. The structural differences between human IgG molecules and camel antibodies.

b. Describe in detail three advantages and one disadvantage of using recombinant scFv fragments instead of whole IgG molecules in therapeutic applications. Explain your choice with reference to the structures of the two molecules.

Answer 1

Immunoglobulin G (IgG) is a type of antibody. In human body IgG is the largest antibody, present approximately 75% of serum antibodies in humans.

Antibodies have Y shaped structure and consist of four parts i.e, two long regions called heavy chains and two short regions called light chains. However, in case of camel blood or serum the antibodies are of small in size. They have only heavy chain fragments, divided into three domains. Structural difference figure attached below:

1 (b) Instead of large size IgG, Recombinant scFv (Single chain variable domain (Fv)) fragments have many advantages: (i) they are small in size, so they can easily produce in large scale (ii) the overall cost of production and manufacturing is less as compare the Monoclonal antibodies, they are cheaper in cost and (iii) they have high penetration rate because of their small size (used as nanobody) and enter easily into the targeted tissue. e.g. cancerous cell.

However, the limitation or disadvantage of Recombinant scFv they antigen-antibody binding affinity is very less, therefore, they are rapidly remove form the blood and results low therapeutic effect. lower binding affinity and rapid clearance from circulation