The ADLib® system is Chiome Bioscience’s drug discovery platform technology.
The drug discovery platform technology of Chiome Bioscience Inc. is a monoclonal antibody generating system providing a diverse array of complete antibodies in vitro, without using immunization. At Chiome Bioscience we call this system the ADLib® system (Autonomously Diversifying Library system).
• How antibodies are obtained with the ADLib® system
- The principal feature of the ADLib® system is the ability to automatically construct a cell library having diversified antibodies by activating DNA recombination in the antibody gene locus.
- The ADLib® system promotes DNA recombination (gene conversion) in the antibody locus of DT40 cells, a cultured cell line derived from chickens. The system collects and propagates only the cells that bind to the target antigen. Generation of monoclonal antibodies against any antigen can be drastically cut to about 1 week from the 3 to 6 months required with conventional techniques.
- Since there is no need to immunize whole animals, the ADLib® system can generate specific antibodies against toxins, pathogens, self-antigens, and the like which were difficult by nature in the past. As newer versions of the ADLib® system become available, it has become possible to generate antibodies against antigens considered difficult to obtain with conventional techniques.
- Since Chiome Bioscience was founded, our goal has been to create technology that will enable everyone to succeed. Standardization and automation of the ADLib® system was the realization of that goal. Chiome Bioscience’s drug discovery platform technology was established through patent rights related to the ADLib® system and Chiome Bioscience’s proprietary operational know-how, including our libraries of cells for realizing diverse antibodies and our selection method. Our platform technology for drug discovery stands on intellectual properties and our own know-hows which make others difficult to copy our technology.
Diversification of Antibody Genes (Diversification through Gene Conversion)
Antibodies are proteins that play a central role in the immune reaction that occurs after the body is infected with a pathogen. There are an infinite number of different pathogens. The body therefore has the ability to remodel antibody genes by DNA recombination and thereby create an infinite number of different antibody genes to deal with any type of pathogen.
Diversification of the antibody locus in humans and mice is accomplished by V(D)J recombination. In contrast, diversification of the antibody locus in animals such as chickens and rabbits is accomplished by gene conversion, which is a type of homologous recombination.
Gene conversion leads diversification of antibody loci in the avian DT40 cell line as well.
• Mechanism of Antibody Diversification in the Antibody Gene Locus
Genes for making antibodies are present in the genome (within the DNA). (Fig. 1)
Each of the pseudo variable region gene here is replaced by a variable region gene as in the photo montage. (Fig. 1 » Fig. 2)
Diversification of the gene sequences that produce antibodies leads to production of a variety of different antibodies. (Figs. 2 » Fig. 3)
In fact, an infinite diversity (variety) of antibodies can be expressed on the surface of the avian DT40 cell by virtue of the fact that the above recombination of genetic sequences occurs in such cells. (Fig. 4)
How the ADLib® System Works
With the ADLib® system, the target antigen for the antibody to be generated is put into a cell library expressing a diverse array of antibodies, and antibodies reacting to the antigen are obtained. A diverse array of antibodies against antigens previously considered difficult are generated in a short time (about 10 days), compared to the conventional antibody generation methods (the mouse hybridoma method and phage display method).
We will use the metaphor of “fishing” to describe the procedures below and antibody generation method depicted in the illustrations. Briefly, you go fishing in a fishing pond where a rich variety of fish are intentionally kept and bred. After catching the one particular type of fish that lays the desired type of eggs, you breed the fish and have it rapidly lay eggs, which you then collect.
Procedure Construction of a Library Containing a Diverse Variety of Cells
- Addition of a Trichostatin A to DT40 cells activates homologous recombination of the genes. The DT40 cells, which have a diverse variety of genetic sequences, then propagate autonomously. This results in the creation of a highly diverse cell population in the library. (Fig. 1 » Fig. 2 » Fig. 3)
Procedure Forming conjugate of Magnetic Beads with the Antigen
- A “trap” is made for catching antibodies that react only with the antigen target (specific antibodies) by conjugating steel microparticles (magnetic beads) with the target antigen. (Fig. 4 » Fig. 5)
Procedure Catching the Specific Antibody that Binds Only to a Certain Target Antigen
- Magnetic beads conjugate with target antigen are placed in the library and allowed to react for about 30 minutes. Cells in the library producing specific antibodies that bind only to the target antigen attach to that antigen. (Fig. 6 » Fig. 7)
- After 30 minutes, a magnet is used to fish out magnetic beads with antibody-producing cells bound to them. (Fig. 7 » Fig. 8)
Procedure Cultivating the Antibody Producing Cells and Having Them Secrete the Antibodies only
- DT40 cells producing the antibody that specifically reacts with the target antigen are collected. Then the cells are cultivated in a nutrient medium for about 1 week. Not only do the cells display antibodies on the cell surface, but they also secrete antibodies in to the medium at the same time. (Fig. 9 » Fig. 10)
- Then the medium is collected without the cells, and the antibodies produced are obtained by separation. (Fig. 10 » Fig. 11)
Procedure Converting the Antibodies to the Human Type to Complete the Operation
- 1. Since the antibodies obtained are chicken antibodies, humanization is performed to convert them to the human type. The humanized antibodies then become the drug candidates. (Fig. 12 » Fig. 13)
ADLib® axCELL: A Technical Application of the ADLib® System
ADLib® axCELL is a practical application of the ADLib® system. ADLib® axCELL is a proprietary technology that Chiome Bioscience successfully developed to obtain antigens from cells for use in the ADLib® system. By using antigens expressed on the cell surface in their unaltered natural state, we can obtain antibodies that are difficult to obtain with conventional methods.