“…In addition they carry two heavy chains and two light chains, and thus it is difficult to genetically manipulate them to construct fusion proteins with other partners. Rapid progress in molecular immunology, combined with the polymerase chain reaction, has made it possible to clone the antibody binding domain (Fv fragment) and express the polypeptide chains in bacteria, yeast, mammalian cells and plant cells either as pure antibodies or as fusion proteins comprising antibodies genetically linked to other peptides [ 29 , 30 ]. By advanced technologies such as phage display, antibody fragments specific for particular antigens can be isolated in vitro from libraries containing diverse repertoires of antibodies V-genes, which bypasses hybridoma technology altogether and generates single-chain antibodies with specificity and affinity similar to monoclonal antibodies.…”