Recombinant Anti-CD3 x Anti-CD4 Bispecific Antibody (scFv-IgG) is formed by an IgG and two scFv fragments. The scFvs from an anti-CD3 antibody variable domain are respectively connected to the N terminus of the anti-CD4 IgG heavy chains or light chains to form scFv-(H)IgG or scFv-(L)IgG. It is a type of appended IgGs and has 2+2 antigen-binding valency. This BsAb can retarget T cells to HIV-1 infected cells. It is designed for the research of HIV-1 infection, AIDS therapy.