We first compared in our AID-Cre-ERT2 × ROSA26-loxP-EYFP mouse system (27) (called AID-Cre-EYFP from now on) serum Ab levels induced by modified aP versus wP vaccine formulations that do not contain diphtheria and tetanus antigens; control mice were injected with adjuvant only (aluminum hydroxide, alum) (Figure 1A). This evidence concerns the gene AICDA and tetanus.