Method for measurement of concentration of antigen

Abstract

The object of the present invention is to provide a detection method that can detect an antigen even if the target antigen has a low molecular weight in a simpler, more efficient, and more stable manner and with higher sensitivity. The detection of the antigen is carried out by using a fusion protein comprising a polypeptide containing a VH domain of an antibody; a given protein; a linker peptide; a partner protein having an activity of binding to the protein and capable of detecting binding to the protein; and a polypeptide containing a VL domain of the antibody; in this order or in inverse order to this order, wherein the presence or absence of the binding of the polypeptide containing a VH domain and the polypeptide containing a VL domain to the antigen induces the presence or absence of the binding of the protein and the partner protein.

Dependencies are inferred from the claim text.