Your Outsourcing Partner for Protein Research and Production Services

To meet the needs of our clients, Exon provides protein characterization of our expressed protein to insure the quality of recombinant protein.

Recombinant Protein Expression

Exon BioSystems is a protein contract research and production services company specializing in recombinant protein expression, protein purification, and protein characterization.

Antibody Engineering

Additional areas of expertise include assay development of G-protein coupled receptor, recombinant vaccine development and recombinant antibody production.


Exon BioSystems is a protein contract research and production services company specializing in recombinant protein expression, protein purification, and protein characterization.

Monoclonal Antibody Development

Rabbit Monoclonal Antibodies

Exonbio offers custom Rabbit Monoclonal Antibody development services using SPIN® (Single Plasma Cell Interrogation) Technology. This proprietary technology screens the immune repertoire of rabbits, creating the power to select desired rare antibodies directly from affinity matured plasma cells.

The Advantage of SPIN® Technology

SPIN® Technology RabMab® /Hybridoma B Cell
Display Technology Single B
Cell Cloning
Start Material Plasma Cells B Cells B Cells B Cells B Cells
Chain Pairing Native Native Native Mixed Native
Timeline 1 Month 4-5 Months 3 Months 2 months 2 months
Diversity High Medium Medium Low Medium

* Timeline from sacrificing immunized animal to identifying clones, phase II-Phase IV:

  • High affinity: Only high affinity antibodies will be selected owing to the isolation of the terminal differentiated plasma cells.
  • Broad spectrum of epitope coverage: We utilize the natural power of the rabbit immune system to obtain antibodies against a broad spectrum of epitopes for a single antigen.
  • Recombinant antibodies ensure the preservation of genetic information.
  • Customer will received both monoclonal and polyclonal end products.


The Benefit of Rabbit Monoclonal Antibody

Rabbits are well-known for mounting a strong immune response against foreign antigens and rabbit polyclonal antibodies are the oldest and most widely used research tools in immunology, Rabbits generally produce better antibodies to many antigens than rodents.

  • Higher affinity and specificity
  • Antibody affinity is typically represented by the equilibrium dissociation constant (KD), a ratio of koff/kon between the antibody and its antigen. While most mouse monoclonal monoclonal antibodies have a KD value in the nanomolar range (KD = 10-9 M), rabbit monoclonals consistently demonstrate higher affinity, with the KD values which can often reach the picomolar level (KD = 10-12 M).

    In an immunoassay, a high affinity means that you can use less antibody with more stringent conditions without worrying about the loss of signal strength, therefore ensured the highest sensitivity with the highest possible specificity.

  • More diverse epitope recognition
  • The rabbit immune system develops more diverse epitope recognition. This is largely attributed to the lower immune dominance and extensive somatic gene conversion and hypermutation of the rabbit immune response. The benefit is that the rabbit immune system will generally yield a wider range of antibodies recognizing unique epitopes.

  • Improved immune response to small-size epitopes
  • Rabbits have a unique immune system which allows them to develop antibodies against small moiety in small molecules, lipids and polymers or subtle changes in epitopes such as post-translational modifications or single amino acid substitutions. The ability of rabbit generating antibodies against small epitopes are recognized and confirmed by large numbers of antibodies against post-translational modifications (e.g. phosphorylation, methylation, acetylation, sumoylation).

Comparison of Rabbit and Mouse Monoclonal Antibodies

mouse Rabbit
Antigen recognition Limited response to small molecules and peptides Narrow spectrum of epitope recognition No response to rodent antigens High response to small molecules ad peptides Recognize more epitopes per protein
Affinity Nanomolar (10-9M) Picomolar (10-12
Quality Often not good for IHC, ICC Excellent for IHC and ICC

Why the Rabbit is a Better Animal for Antibody Development

B cell development and repertoire diversification vary significantly among species. Diversification of the Ig repertoire occurs through the combinatorial joining of multiple V, D, and J gene segments for the Ig heavy and light chains through VDJ Rearrangement, followed by somatic mutagenesis upon subsequent B-cell encounter with foreign antigen (Somatic Hypermutation). Compared to humans and mice, which use a diverse assortment of germline VH gene segments during VDJ rearrangement of the heavy chain, the rabbit IgH repertoire displays highly restricted VH gene segment usage.

The rabbit and chicken immune system generates antibody diversity and optimizes affinity by mechanisms that are more efficient than those of mice and other rodents. Other than the common Somatic Hypermutation, Rabbit and chicken B cells also employed a mechanism called Gene Conversion, which involves the non-reciprocal homologous recombination of upstream pseudo V gene loci into the recombined VDJ (and VJ) locus. The gene conversion with the approximate of 300 pseudo V-genes dramatically enhanced the diversity of its antibody repertoire and increased the possibility of generating functional antibody clones.


Fifty-million-year-old polymorphism at an immunoglobulin variable region gene locus in the rabbit evolutionary lineage Proc. Natl. Acad. Sci. USA 1999 96:9710-9715

Patented SPIN® Technology

The success of single memory cell based monoclonal antibody technology used in generating HIV neutralization antibody, inspired us to develop a single plasma cell based approach to develop monoclonal antibody. Plasma cell and memory cell are the two types of terminal differential cells harboring the fully matured antibody clones. There are cell surface markers available for memory cells and plasma cells in human and mouse. In order to isolate plasma cells from other common antibody generating animals, such as rabbit, chicken, llama, we developed a new approach that is capable of isolating the plasma cells from these species in a high accuracy. That discovery is covered under US patent.

The Benefits of the Rabbit Immune System and SPIN® Technology

The nature of the rabbit immune system generates better and broad antibodies. However, current hybridoma technology and phage display technology can't effectively retrieve the best antibody from the large amount of low affinity or non-specific clones. Our new Single Plasma Cell Interrogation (SPIN®) technology has the following benefit and is capable to retrieve the rare but best clones from the millions of B cell clones.