Ultralong CDR3 Antibody Discovery via DNA Immunization

With years of experience in antibody discovery and development, Creative Biolabs is proud to integrate the novel DNA immunization approach with our ultralong CDR3 antibody discovery services. With the in vivo antigen expression carried by genetic immunization, we can produce ultralong CDR3 antibodies that have a superior probability to against the naïve conformation of interest antigens.

DNA Immunization

DNA immunization, also known as genetic immunization, is a straight-forward method to induce immune reaction against a foreign protein. Unlike other common immunization approaches, DNA immunization allows in vivo antigen generation, through omitting the time-consuming or difficult processes of immunogens, such as peptides and recombinant proteins production and purification. Meanwhile, it is very powerful to induce both humoral and cellular immune responses, which made this technique successfully applied to the production of high-affinity polyclonal antibodies (pAbs) and high-quality monoclonal antibodies (mAbs). Besides, DNA immunization is a crucial approach for producing mAbs which enable to be used for Ab-based therapies against native forms of membrane proteins (e.g. CD30 and Ret protein). In addition, it has exhibited enormous potential for DNA vaccination development, in which plasmid DNA is injected into an individual, resulting in the host immune system to respond to the antigen.

The X-ray crystal structure of one bovine antibody repertoire with exceptionally long CDR3H loops, BLV1H12. This antibody exhibits a novel structural feature in which CDR3H folds into a disulfide cross-linked “knob” domain fused to an antiparallel β-stranded “stalk”, which is ~20 Å in length and highly solvent-exposed.

Ultralong CDR3 Antibody Discovery

The complementarity determining regions or CDRs are the most pivotal structure parts on an antibody that recognize the antigen. Different from common antibodies where the VH CDR3 loops across species general range from 10 to 25 amino acids, the bovine VH CDR3 enable to be massive in size given its wide heterogeneity extending from 3 to 66 amino acids. Remarkably, about 10% of bovine antibodies have ultralong VH CDR3 regions that possess 35-60 aa. Researchers have demonstrated that antibodies with unusually long VH CDR3 regions are possibly more potent in defense against disease than conventional antibodies.

The ultralong CDR3 confers special “knob and stalk” structural architecture where the knob is separated by 20 Å solvent exposed stalk composed of antiparallel beta strands. The substitution of the knob with cytokines leads to the expression of functional fusion proteins with increased pharmacokinetics. The beta stranded stalk enables to be replaced by other rigid structures (e.g. repeat alpha helices to form coiled-coil that mimics the beta-stranded stalk and), thus opens opportunities for insertion of this structure in the CDRs of antibodies across species. Therefore, the ultralong CDR3 region contributes greatly to the novel development of diagnostics, therapeutics, vaccines, and immunomodulating drugs.

DNA Immunization Approaches Provided by Creative Biolabs

Based on our high-quality DNA immunization strategy, Creative Biolabs enables the development of ultralong CDR3 antibodies with high affinity against a full range of antigens. Our scientists can also generate ultralong CDR3 antibodies from a much broader species than conventional to meet our clients’ specific research goals.

In addition to the ultralong CDR3 antibody discovery services, Creative Biolabs can also provide other customized services via DNA immunization, such as:


  1. Liu, T. (2015). “Rational design of antibody protease inhibitors.” Journal of the American Chemical Society, 137(12), 4042-4045.

All listed services and products are For Research Use Only. Do Not use in any diagnostic or therapeutic applications.

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