1. In situ gene replacement is employed in the generation of the RenMab™ Mouse
The RenMab™ Mouse was designed and developed based on Biocytogen’s unique chromosome engineering technique. In this model, the parts of the genes that encode for antibody variable domains of heavy and κ light chains are fully replaced by human sequences.
Heavy chain: The genes (about 2.6 Mb in length) that encode for murine antibody variable domains were replaced with the human variable domains (about 1 Mb in length, containing all human V/D/J antibody genes, Figure 1A).
κ light chain: Genes that encode for the variable domains of human κ light chain have two copies in opposite directions, namely proximal V cluster and distant V cluster. The coding region of the proximal V cluster is intact, which is frequently selected for antibody gene replacement in other humanized mouse models. Although the distant V cluster lacks the C gene and is considered to be a pseudogene, V and J genes are still potentially functional. We replaced the genes (about 3.2 Mb in length) that encode for murine antibody variable domains with the human counterparts (about 1.6 Mb in length) containing the two opposite-direction gene copies (Figure 1B).
Fig. 1 Mouse variable regions of the heavy and k light chains are replaced by the human counterparts in situ
2. Complete human antibody germline utilization in the RenMab™ Mouse for fully human antibody drug development
As a result of the full humanization of the antibody gene in the variable domains, the RenMab™ Mouse expresses more diverse antibody molecules than other commercially available humanized mouse models. The components of different antibody isotypes in the sera of the RenMab™ Mouse are nearly identical to those of the wild-type mouse. The genes that encode for human antibody variable domains in the RenMab™ Mouse can be widely used, with a full diversity of VDJ recombination as confirmed by CDR analysis. Taken together, the RenMab™ Mouse can produce a diverse repertoire of fully human antibodies for therapeutics discovery.
3. RenMab™ Mouse has a completely developed immune system comparable to that of wild-type mouse
Another major benefit of the RenMab™ Mouse’s design strategy is the maintenance of an intact immune system as confirmed by the complete analysis of the immune organs and tissues of the RenMab™ Mouse. Our data has revealed that is no significant difference between the immune cells and immune tissues of the RenMab™ Mouse and that of wild-type mouse. Such integrity of the immune system of ensure the superior efficiency of RenMab™ Mouse for the generation of antibodies over any other humanized mice models.