Your Outsourcing Partner for Protein Research and Production Services

To meet the needs of our clients, Exon BioSystems 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.

Biologics

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

Products

Chicken IgY monoclonal antibody

Chicken IgY antibodies are the avian equivalent of mammalian IgG antibodies. The phylogenetic distance from mammals make chicken-antibodies suitable for conserved antigens.


Unlike other chicken monoclonal antibody service providers, exonbio uses SPIN® technology to isolate the specific plasma cells that are against a specific antigen. We amplify and clone the native antibody heavy and light chain pairs from single plasma cells. This step reduces screening time in finding a wide diversity of potentially functional clones and results in significantly higher affinity for the antibodies we obtain.

  • Higher affinity and broader diversity
  • Better antigenicity for mammalian antigens
  • Higher specificity and low cross-reactivity

Chicken Immunization

Mice have historically been the animal of choice for making monoclonal antibodies, because the hybridoma technology was developed for mice. Rabbits, (or other large animals) have been used to make polyclonal antibodies because they are larger than mice, and it is possible to collect more antibodies from their blood serum. However, some antigens fail to induce an immune response in mammals, especially those that are highly conserved. Rats, mice, rabbits, and primates (us) are all members of the same larger mammalian group (Euarchontoglires), and some highly conserved proteins do not elicit an immune response among members of this group. However, birds and mammals diverged from one-another over 300 million years ago, and this evolutionary time gap reduces the similarity across even highly conserved proteins, and thus, increases antigenicity. Thus, proteins that fail to initiate an immune response in mice or rabbits, will often elicit a vigorous response in chickens. All vertebrates share similar immune machinery, so chicken antibodies can work in applications were mammalian fail. In addition, Chickens produce much more antibody than mice by secreting their antibody to eggs.

In early days, the lack of robust technology for making chicken monoclonal antibodies was simply a historical artifact. G. Kohler and C. Milstein developed monoclonal antibody technology using mouse hybridomas in 1975. In 1995, Katherine Knight and her colleagues at Chicago's Loyola University developed hybridoma technology for rabbits. Recently, Phage Display technology has made chicken monoclonal antibody possible.

SPIN® Technology or Phage Display

Phage display allows for the rapid selection of monoclonal antibodies without the constraints of conventional hybridoma techniques. However, the utility of phage display technology for monoclonal antibody production in chickens has been limited. The mixture of heavy chains and light chains from different B cells exponentially increases the size of the library screening eventually becomes prohibitively time-consuming and expensive. Phage preferences can introduce strong non-target biases that favor nonfunctional parasitic clones over the desired clones.

To avoid this defect, we developed a SPIN® (Single Plasma Cell Interrogation) Technology. Compared to phage display, SPIN® for chicken monoclonal antibody production is more robust and much less biased in clone selection. Antibodies generated by SPIN® have higher diversity and affinity than those generated by traditional approaches.

The Avian Immune System

Chickens, like mammals have both humoral and cell mediated arms of the adaptive immune system (Erf 2004; Scott 2004; Sharma 1991). Birds have a unique hematopoietic organ; an outfolding of the cloaca called the Bursa of Fabricius. Glick and colleagues (1956) demonstrated that the Bursa of Fabricius is essential for normal B cell development and humoral immunity in birds. Precursor B cells have rearranged their immunoglobulin genes prior to entering the bursa. Compared to mouse, rat and human immune systems, the chicken contains a very limited number of variable genes. Instead, chickens use a process termed "gene conversion" (Wysocki and Gefter, 1989) to create antibody diversity, where the variable heavy and light chains are replaced with upstream pseudogenes (Benatar et al., 1992), under a similar convergent mechanism as rabbit immunogenetics. While only one variable (V) light chain, one joining (J) light chain, one V heavy chain, one J heavy chain, and sixteen D heavy chains are initially available for gene rearrangement, approximately 25 V light and 80 V heavy pseudogenes can be inserted to create antibody diversity.

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