Why Are Rabbit Antibodies A Sought-After Tool?

From analytical applications (e.g., Western blot, ELISA, and Immunostaining) to diagnostics (e.g., detection of tumor-associated antigens: PDL-1, estrogen receptor, and HER2) and even as therapeutics (e.g., Brolucizumab, Eptinezumab), rabbit monoclonal antibodies are attractive and powerful tools.

For therapeutic use, the higher sensitivity and epitope specificity of rabbit monoclonal antibodies translate to reduced off-target binding and lower dosage requirements, ultimately minimizing the potential for toxicity.

Broader Antigen Detection Capabilities- Rabbit monoclonal antibodies offer more expansive target recognition capabilities ideal for diagnostics and therapeutics. Broader paratope diversity is underscored by the unique processes giving rise to the primary antibody repertoire in rabbits, which depends on somatic hypermutations, as occurs in mice, but also on somatic gene conversion, a type of homologous recombination predominant in the chicken and rabbit.

Expanded Opportunities for Screening - The rabbit’s general larger size, notably larger spleen and greater blood volume and bone marrow tissue, translates to greater opportunities for isolating B cells and finding more monoclonal antibodies with desirable epitope specificities.

Cross-reactivity is a Plus- An added advantage of rabbit-derived monoclonal antibodies is their cross-reactivity with epitopes in mouse and human antigens, which is helpful in preclinical evaluation and characterization of human disease mouse models.

Low Immunogenicity Antigens-Not a Problem- The rabbit’s immune system can recognize human antigen epitopes that are otherwise ignored by that of rodents.

If your target of interest happens to have low immunogenicity, as is typical for small molecules, rabbits may be your best choice for monoclonal antibody development. Unlike rodents, rabbits can mount a stronger immune response against small molecules, haptens, and post-translational modifications (e.g., AMPylated peptides and phosphorylated peptides). 

About critical considerations to keep in mind when developing monoclonal antibodies against post-translational modifications, Dorothea Hopfner shared that antibodies must-

• Recognize small moieties with high affinity
• Recognize small but important differences between different post-translational modifications (e.g., di- and tri-methylation)
• Lastly, if the antibody is to be used for new target identification, a desirable property is that the antibody is able to recognize post-translational modifications independently of protein sequence

In developing anti-PTM antibodies, synthetic peptides are an asset. “Synthetic peptides can significantly help in anti-PTM antibody development, and the bottleneck of antibody candidate selection can be overcome by including native modified protein for screening when immunizing with peptides,” said Dorothea Hopfner.

Overall, the enhanced properties of rabbit antibodies represent an advantage for applications requiring high sensitivity and epitope specificity. Whether you select a rabbit polyclonal or monoclonal antibody ultimately depends on your specific needs. For the detection of AMPylated proteins, Dorothea Hopfner required a long-lasting, consistent, and reliable antibody source to support characterization and validation efforts. Therefore, a rabbit monoclonal antibody was the best choice to prevent batch-to-batch reproducibility issues.

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