The present invention provides methods for the diagnosis, prognosis and treatment of HCV-related disease. The method takes advantage of a novel reactive mechanism of the murine monoclonal antibody (mAb) 1F7 against human antibodies specific for different proteins of the Hepatitis C Virus (HCV) and Human immunodeficiency virus (HIV). 1F7 recognizes antibodies against HCV core protein in a majority of HCV-infected individuals and antibodies against HCV non-structural proteins 3 (NS3) and NS4 in some HCV-infected individuals. 1F7 also recognizes antibodies against the putative principle neutralizing determinant (hypervariable and conserved region 1 of the HCV E2 protein) of HCV. The antibody can be used in various methods to detect HCV related disease and formulated with physiologically acceptable carriers in various compositions to treat HCV infection.