The antibody refers to an immunoglobulin produced by the body under the stimulation of antigenic substances. It can combine with bacteria, viruses, mycins and other substances to play a role in preventing and treating diseases. Monoclonal antibody, as a kind of antibody, is the largest category of products in the biopharmaceutical industry. The specific synthesis method is shown below. The currently prepared antibodies are all of murine origin. In clinical applications, murine origin is a heterogeneous antigen for humans, and repeated injections will cause human anti-mouse antibody reactions. As a result, the effect of the antibody will be weakened, and hypersensitivity reactions will occur in severe cases. Therefore, genetically engineered antibodies can greatly reduce the immunogenicity of mouse antibodies.
Fig.1 The process of murine monoclonal antibody production
Through gene recombination technology, the antibody gene is processed, transformed and reassembled. After transfection with appropriate recipient cells, the tailor-made antibody molecules are expressed. These antibody molecules modified by antibody engineering methods are new types of antibody molecules , which can retain (or increase) the specificity and main biological activity of natural antibodies, remove (or replace) irrelevant structures. Therefore recombinant antibodies are more promising than natural antibodies.
Fig.2 Gene recombination in the preparation of humanized antibodies
htDNA-chip® high-throughput platform has the following applications in recombinant antibodies, including the construction of antibody libraries for antibody screening and the preparation of various customized antibodies.
Antibody libraries can be constructed using the htDNA-chip® technology platform by cloning the full set of antibody heavy and light chain variable region genes. And then recombining the genes into specific prokaryotic expression vector phages. The technology of transforming genes into Escherichia coli to express functional antibody molecule fragments, and obtaining specific antibody variable region genes through affinity screening. The antibody genes screened by antibody library technology will be used to construct and express genetically engineered antibodies.
Fig.3 htDNA-chip® in the antibody library construction
The chimeric antibody was spliced from the V region (amino terminal) gene of mouse antibody and the C region (carboxyl terminal) gene of human antibody into chimeric gene, which was then inserted into the vector and transfected into the antibody molecule expressed in myeloma tissue.
Human-derived antibodies replace the complementary determinant regions(CDR) of murine monoclonal antibodies with the CDR of human antibodies. The resulting antibodies are of only a small proportion of murine origin.
The mouse immunoglobulin gene is knocked out by gene knockout and replaced with the human immunoglobulin gene. Then the mice are immunized with antigenic group, and then a large number of fully humanized antibodies can be produced by hybridoma technology.
The single-chain antibody connects the H chain and the V region genes of the L chain of the antibody, and transfects the antibody molecule expressed in E. coli.
The antibody that recognizes the effector cell and the antibody that recognizes the target cell are linked together to make a bifunctional antibody.
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