Single-chain molecule (I) that binds multiple antigens comprises two variable domains of heavy immunoglobulin chains (VH), having specificities A and B and two variable domains of light chains (VL), also with specificities A and B. The domains are provided as two VH-VL constructs which are attached via a peptide (P). Any VH and VL may be replaced by their functional fragments. Independent claims are also included for the following: (1) nucleic acid (II) encoding (I)； (2) vectors containing (II)； (3) cells containing (II) or the vectors； (4) recombinant production of (I) by culturing these cells； (5) pharmaceutical composition containing (I), (II), the vectors or cells； and (6) diagnostic composition containing (I). ACTIVITY : Anticancer； antiviral； antibacterial； antimalarial； antiinflammatory. MECHANISM OF ACTION : Specific binding interaction.
