Expression and purification of monospecific and bispecific recombinant antibody fragments derived from antibodies that block the CD80/CD86-CD28 costimulatory pathway

Construction and expression of D-dimer and GPIIb/IIIa single-chain bispecific antibody

The aim of this study was to construct a plasmid expressing glycoprotein IIb-IIIa (GPIIb/IIIa) and D-dimer single-chain bispecific antibody for the targeted therapy of thrombosis. The phosphorylated gene encoding the anti-GPIIb/IIIa single-chain variable fragment (scFv) and the gene encoding the anti-D-dimer scFv were amplified by PCR and linked in tandem by blunt-end ligation. The recombinant plasmid was transfected into the competent cell line HB2151 and identified by PCR and DNA sequencing. Then, the soluble recombinant antibody in bacterial lysates was purified by an NTA column and molecular sieve chromatography in turn. Finally, the binding specificity of the purified antibody was tested by enzyme-linked immunosorbent assay (ELISA). Results demonstrated that the construction of the expression plasmid was successful and the purified recombinant protein, which had a molecular weight of ∼56 kDa, was specific to GPIIb/IIIa and D-dimer. In conclusion, a plasmid expressing a bispecific antibody was constructed by a new method of blunt-end ligation. The soluble recombinant protein is a promising platform for target-oriented thrombolytic therapy.

Optimizing expression and purification from cell culture medium of trispecific recombinant antibody derivatives

Antibody fragments offer the possibility to build multifunctional manifolds tailored to meet a large variety of needs. We optimized the production of a manifold consisting of one (bibody) or two (tribody) single-chain variable fragments coupled to the C-terminus of Fab chains. Different strong mammalian promoters were compared and the influence of expression media on production and recovery was investigated. Since the physical and chemical nature of these molecules largely depends on the nature of the antibody building blocks incorporated, a generally applicable process for the purification of recombinant antibody derivatives from serum containing mammalian cell culture medium was designed. To this end we compared protein L, hydroxyapatite, immobilized metal affinity chromatography, cation-exchange chromatography and hydrophobic charge induction chromatography.