Recombinant Anti-Ad fiber knob x Anti-CD40 Bispecific Antibody (scIgG) is designed to be expressed as two chains, each chain has the same units with their parental IgG antibodies, anti-Ad fiber knob and anti-CD40 IgGs. The two chains form heterodimer via Fc KIH technology. This BsAb can retarget of adenoviral vectors to tumour cells. It can be used in cancer gene therapy to transfer a therapeutic gene into tumour cells aiming at selective and efficient cell killing.