Recombinant Anti-TG x Anti-TPO Bispecific Antibody (scFv4-Ig) is an appended IgG format, which includes four scFv moieties at the N-termini of the constant regions. It is a bivalent homodimer, in which one anti-TG scFv is fused to the CH1 domain of a heavy chain and another anti-TPO scFv to the CL domain of a light chain, or vice versa. The resulting leads to 2+2 antigen-binding valency. This BsAb can bind two antigens simultaneously and block the synthesis of thyroid hormones. It is designed for the research of Autoimmune thyroid disease therapy.