Construction Of Single-chain Light Variable Region(ScV_L) Library Of Chicken IgY Genes By T7 Phage Display Technology

Three immunoglobulin classes have been shown to exist in chicken. IgY, IgM and IgA. The anti-maladies function of IgY is similar to mammalian IgG, but the structure of IgY is different to mammalian IgG. IgY is composed of two heavy chains and two light chains, but no hinge region on the heavy chain. The antigen binding regions are formed by the interaction of the variable light (V_L) and variable heavy (V_H) domains at the amino termini of the chain. The three complementarity-determining regions (CDRs), located in the variable region, are the specific bound regions with antigen epitope. It has been shown that V_L of IgY is encoded by the V_λ and J_λ genes. The mechanism of IgY light chain diversity in chicken depends on gene conversion during bursa of fabrrcius maturity, and the affinity of IgY for antigen will increase through somatic diversification stimulated by antigen.Due to greater phylogentic difference between avian and mammalian species, the immune response of chickens to mammalian proteins is strong. That is to say, it is easy to obtain specific IgY from chicken immunized with evolutionary conserved mammalian proteins as antigens. IgY is transported from the serum to the egg yolk and stored in it, and then transmitted to the developing embryo from egg yolk. High immunized eggs can be obtained after several times immunization, and the IgY can be extracted and purified from egg yolk with biochemical methods. Many studies have indicated that chicken IgY has high specificity, which analogues to mouse monoclonal antibody. Chicken IgY is stable against heat and acid. Most of the antibody activity will remain under 70℃ or at pH above 4. Using chickens to produce antibodies brings more advantages than mammalian: collection and storage of high immunized eggs is very simple, and producing larger amounts of antibodies is easy. It also makes it possible to eliminate the collection of blood and bleeding which has an advantage concerning the welfare. Since it is very popular to produce IgY. there are IgY products on the market.Using IgY has its advantages but there are disadvantages. (1) There is too many diseases in chickens, particularly the avian bird influenza, the disease infecting both people and avian. The high demanding in safety is required about chicken IgY. Experts suggested that SPF chickens should be used to produce the IgY. It cannot be difficult to imagine that the cost of IgY producing will be very...