What portions of the antibody gene should be cloned for the generation of recombinant antibodies?

There are four different approaches when it comes to cloning recombinant antibodies. Both heavy and light chains are cloned in order to generate full-length IgG antibodies. The Fab fragment, which is the antigen-detecting portion of the antibody, is cloned only when trying to generate monovalent recombinant antibody proteins. The scFv portion of the antibody forms a functional antigen-binding site and can be used as a vehicle for drug candidates. The single-domain antibody fragment is another portion that can be cloned and consists of the variable region of the heavy chain.