One Step Hepatitis C Virus Antibody Test Hepatitis C virus now us recognized as a major agent of chronic hepatitis, transfusion-acquired non-A, non-B hepatitis and liver disease throughout the world. HCV is an enveloped positive-sense, single-stranded RNA virus. Clinical diagnostic issues related to HCV is the detection of HCV antibodies in human serum or plasma by immunoassay. We have constructed HCV genes for the expression of recombinant antigens in bacterium systems such as E.coli and focused on structural and non-structural regions of HCV encoded polyprotein, which war definitely immunogenic. The major immunoreactive antigens of these proteins have been reported as core, NS3, NS4 and NS5 regions of HCV genome, which are known to be highly immunodominant regions. For diagnosis HCV infection, theses recombinant proteins were used as capture materials of a immunochromatographic test. Compared to the first generation HCV test using single recombinant antigens, multiple antigens using recombinant proteins have been added in new serologic tests to avoid non-specific cross reactivity and to increase the sensitivity of the HCV antibody test.