Choose the right immunization host for your antibody discovery campaign
Integral Molecular scientists begin each MPS Antibody Discovery project with a detailed target assessment to recommend the most appropriate immunization host. The right host will provide robust immune responses, the ability to generate functional antibodies, and an opportunity for expedited preclinical development in standard animal models.
Chicken immunization with one-step hCAT humanization
Our patented Humanized Chicken Antibody Discovery Technology (hCAT) isolates fully humanized, affinity matured antibodies directly from immunized animals, eliminating the time and cost required for downstream antibody engineering. This process involves humanizing antibody sequences obtained from chickens prior to the creation of immune libraries used for phage panning. hCAT uses a single germline framework and synthetic/germline CDRs for enhanced developability, and CDR shuffling to enable affinity maturation in the picomolar range.
Transgenic ATX-GxTM humanized mice
The MPS platform can utilize ATX-GxTM transgenic, humanized, immunocompetent mice for antibody discovery campaigns to produce antibodies that are fully human and highly developable. Integral Molecular is a Certified Provider of Alloy Therapeutics who provide ATX-GxTMmice.
How do MPS Antibody Discovery campaigns succeed for membrane proteins when other platforms fail?
HINT: Antibody discovery in chickens provides access to more drug targets
of human drug targets are inaccessible in mice due to high sequence conservation
With 310 million years of evolution between chickens and humans, chickens mount a robust immune response for most targets
Advantages of chickens for antibody discoveryCritical to Integral Molecular’s >95% success in antibody discovery
Antibody discovery has historically used mice for immunization to create antibody producing hybridomas. While mice have been exceptionally successful for antibody discovery against numerous uncomplicated targets, their inability to mount immune responses against high-homology targets has hindered discovery efforts. This limitation of murine immunization hosts is a major reason why traditional antibody discovery campaigns struggle with multipass membrane proteins and are successful only ~30% of the time—and even then, only for the easiest membrane proteins. MPS uses strategies such as chicken immunization and advanced immunization techniques coupled with phage display. This combines the power of a robust immune response in divergent animals with deep screening to select antibodies with the right characteristics.
Complex membrane proteins are often highly conserved and do not produce a robust immune response in mice due to immune tolerance. In our experience spanning thousands of immunization campaigns, proteins with 90-100% sequence identity to their host counterparts mount extremely poor immune responses. For mice, half of all drug targets show this high conservation.
With approximately 310 million years of evolution between chickens and humans, the chicken immune system is much more capable of mounting an immune response to human drug targets. We have obtained robust immune responses for numerous high-homology targets including ion channel Kv1.3, transporter SCL2A4, and Claudin 18.2 (see our pipeline). These targets are >90% identical between mice and humans and would have insufficient immune responses and limited epitope diversity after mouse immunization.
The paratope is the region of the antibody that contacts the target protein and is primarily composed of an antibody’s HCDR3. Long HCDR3 regions are more likely to form protruding paratopes that can reach into functional pockets and modulate a protein’s function. Our antibody discovery programs have generated numerous molecules with long paratopes and rare functional activity. HCDR3 length distributions vary by animal, with chickens having longer HCDR3 regions relative to other typical immunization hosts.
Average HCDR3 lengths: chickens 16aa, rabbit 13 aa, and mouse 9 aa (as denoted using the Kabat numbering scheme).
Antibodies developed in mice are rarely compatible with testing in standard preclinical rodent models because they do not bind the corresponding rodent protein. Consequently, most antibodies have required preclinical testing in non-human primates. Numerous examples in the literature and our own pipeline describe chicken antibodies that cross-react in several species including rat and mouse, making preclinical studies faster and enabling lower usage of non-human primates.