Goat Polyclonal Antibodies

A polyclonal antibody preparation contains antibodies from multiple B cell clones, each of which recognizes a unique epitope on the same target protein. This heterogeneity means that polyclonal antibodies can often improve assay sensitivity compared to using monoclonal antibodies, which 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, cross-linking, or the formation of protein complexes. A further advantage of being able to recognize multiple epitopes is that polyclonal antibodies may have broader application functionality than monoclonal antibodies. For example, a polyclonal antibody may be capable of detecting a native protein by immunohistochemistry (IHC) and its denatured form by western blotting (WB), while a monoclonal antibody may only work in one of these applications. Other general advantages of polyclonal antibodies include their relatively low cost and faster availability when a new target (e.g., SARS-CoV-2) is discovered. While polyclonal antibodies can be produced in several different species, goats are the preferred hosts for generating polyclonal antibodies in larger amounts. Compared to rabbits (the main species used for polyclonal antibody production), goats are estimated to produce around 7-8 times the amount of serum and 2-3 times the total concentration of IgG (typically around 20 mg/ml). Not only does this provide more antibody from the same animal, which can improve experimental consistency, but it also means that the cost per mg is usually lower. Goat polyclonal antibodies also simplify multiplexing with mouse, rat or rabbit antibodies when using indirect detection since anti-goat secondary antibodies are unlikely to cross-react with rodent or rabbit IgG. However, a limitation of using goats for polyclonal antibody production is that they should be 1-2 years old before being immunized, which equates to higher upkeep costs and requires forward planning to ensure enough animals are available to meet demand, and may be a factor in the relative popularity of chicken polyclonal antibodies and rabbit polyclonal antibodies.