Chicken Polyclonal Antibodies

Polyclonal antibodies offer many advantages for scientific research, including the potential to improve assay sensitivity. Because each polyclonal antibody preparation contains a mixture of antibodies that all recognize different epitopes on the same protein, signal amplification can be achieved as a result of multi-epitope binding. This property of polyclonal antibodies can be especially useful when detecting scarce targets, or proteins that are likely to change conformation, as well as when performing techniques such as immunohistochemistry (IHC), immunoprecipitation (IP), or chromatin immunoprecipitation (ChIP), when certain epitopes may be masked by fixation, crosslinking, or the formation of protein complexes. Other advantages of polyclonal antibodies include their relatively low cost and faster availability than monoclonal antibodies when a new target is discovered, which are consequences of their easier method of production. Polyclonal antibodies may also have broader application functionality than monoclonal antibodies, such as being able to recognize both the native and denatured forms of a protein. While polyclonal antibodies are typically produced in mammals, and are commonly of the immunoglobulin G (IgG) isotype, such as rabbit polyclonal antibodies and goat polyclonal antibodies, chicken immunoglobulin Y (IgY) antibodies are increasingly popular among researchers. Compared to antibodies raised in mammalian hosts, chicken polyclonal antibodies will usually react with more epitopes on a mammalian antigen due to the greater evolutionary distance between birds and mammals, which can lead to signal amplification. In addition, the high carbohydrate content of chicken IgY enables a greater degree of enzyme, fluorophore, or hapten conjugation away from the antigen-binding regions of the antibody. Another advantage of chicken polyclonal antibodies over mammalian polyclonal antibodies is that their production is more straightforward. While mammalian antibodies must be extracted from the blood, chicken antibodies are actively transported from the serum to egg yolks, from which they are easily removed and purified. This has the associated benefits of improving animal welfare and lowering production costs. Chicken antibodies are also generated in far greater quantities than rabbit polyclonal antibodies (the most common type of polyclonal antibody), with a standard immunization protocol achieving comparable yields to those of a larger animal like a goat or sheep. The IgY isotype also provides several further advantages. Most notably, chicken polyclonal antibodies simplify multiplexing with mammalian antibodies when using indirect detection as anti-chicken IgY secondary antibodies do not cross-react with mammalian IgG. In addition, because the Fc regions of the IgY heavy chains are distinct from those of mammalian IgGs, chicken polyclonal antibodies are less likely to cause interference in immunological assays by reacting with components such as Fc-receptors, rheumatoid factors, or proteins of the complement system, or in immunoassays where antibody binding to Protein A or Protein G must be avoided.