Anti-peanut antibodies were tittered using ELISA. In short, each of the 96 wells of the microtitration plates (Global Plast, China, 655111T) was adsorbed with 100μl of saline buffer containing 2μg of the specific protein extract. A 3-fold serial dilution of the sera was performed, and HRP goat anti-mouse γ-chain was used (SIGMA, Saint Louis, MO, United States A9044). The result was registered using a microtitration plate reader (Anthos 2010^, Biochrom, Cambourne, Cambridge, UK). Reactivity analysis was performed by comparing the area under the dilution curve. The serum of each mouse was tested 4-fold, i.e. on four microtitration plates adsorbed each, with one of the 4 protein extracts.