Effect Of Irradiation On Bio-chemistry And Antigenic Properties Of Allergen In Shrimp

Food allergy, a special type of foodborn desease, is currently of concern in the world. According to epidemiological investigation, food allergy affects 2%～2.5% of total population and about 5%～8% of enfants and infants annually in America. About 600 cases of food allergy are reported annually in Australia, and allergic foods account for 47% in the recalled foods in 2004 in Australia. According to incomplete statistics, morbidity of food allergy in our country is high than the developed countries, and food allergy caused by shrimp is very common these years. Crustacean including shrimps,crabs and their produces is one of the eight kinds of allergic foods in the FAO list of allergic foods. Since muscle tropomyosin (TM) was reported as the major allergen among shrimp allergens, many researchers have indicated that the protein is a heat-stable protein with molecular weight of 36 kDa. Lee.YK.and Myung-Woo Byun reported that the surface epitopes on muscle myosin could be changed, i.e. degraded, coagulated and molecular modification by gamma irradiation, so irradiation will be a promising approach for decreasing the allergenicity of alergen. The objectives of this papers were to conform the allergenicity deduction by irradiation and figure out its principle. Shrimp allergen were extracted and purified using SDS-PAGE and polyclonal antibody of the allergen was prepafred. Shrimp allergen (troppomyosin) in different forms, freezer-dryed powder, the whole shrimp and allergen solution were irradiated at different dosages, 0, 3, 5, 7, 10 kGy, the effects of irradiation on its biochemistry and immunology were investigated with an aim to figure out the moleculer principle of immunology through irradiation and to provide the knowledge of allergenicity deduction by irradiation.The results indicated that biological chemistry properties such as the moleculer structure, hydrophobicity and turbidity of shrimp allergen were changed due to Allergen moleculer degradation, coagulated and so on.The affinity of irradiated TM binding to polyclonal antibody and IgE of patent allergic to shrimp was examined by ELISA. It was found that after boiled treatment, shrimp allergen could still strongly binding to IgE of patient allergnic. And shimp allergen (TM) after treating with irradiation, the affinity of IgE of patient allergnic to shrimp and mouse polyclonal antibody IgG binding to irradiation TM were dose-dependently reduced. The results indicated that antigenic properties of shrimp allergen was changed and the allergenicity could be reduced by irradiation. The results also indicated that the allergen was more sensitive to irradiation in solution than that in solid form or in the shrimp.Above results showed that shrimp allergen (TM) was conformational modification by irradiation through degrdation, coagulated and other chemical reaction. The biological structure was changed and the antigen epitodes was also changed. This study shows that allergenicity of shrimp reduced by irradiation technology.