Recombinant Anti-BAFF x Anti-B7RP1 Bispecific Antibody (Single-chain Diabody) is designed to be expressed as one polypeptide chain with four variable domains from two parental antibodies. The middle linker is long enough to form scFv dimers between the two diabody chains. This BsAb can bind and inactivate two ligands simultaneously. It can inhibit B cell survival and T cell costimulation. It is designed for the research of Systemic lupus erythematosus (SLE) therapy.