Abstract: A method for extracellularly producing an ectoprotein of hepatitis C virus comprises the steps of cultivating a transformant which is transformed with an expression vector containing a DNA fragment coding for the ectoprotein of hepatitis C virus and recovering the ectoprotein of hepatitis C virus extracellularly produced by the transformant. The protein originated from the E1 region prepared by the method can be used as a material for preparing a vaccine for preventing HCV infection. In addition, a diagnostic agent containing the protein is useful for the detection of an HCV antibody or the confirmation of the presence thereof in sera or the like. In other words, the protein of the present invention permits the diagnosis of C type hepatitis in high specificity and sensitivity.

Abstract: A vaccine containing Mycobacterium bovis BCG which secretes a fusion protein to be obtained by inserting a foreign antigen peptide into the molecular surface of a secretory protein, a carrier, having a signal peptide. BCG constituting the present invention secretes a fusion protein to be obtained by inserting a foreign antigen peptide into the molecular surface of an .alpha.-antigen derived from mycobacteria. Said fusion protein has significantly increased antigenicity and immunogenicity. Therefore, when it is inoculated into animals, it is efficiently recognized by B cells which recognize said antigen, thereby effectively inducing the production of an antibody to said antigen. When said BCG itself is inoculated into animals, it continuously secretes said fusion protein in the bodies of the animals while continuously propagating therein. Therefore, said BCG is an extremely useful vaccine.

Abstract: A vaccine containing Mycobacterium bovis BCG which secretes a fusion protein to be obtained by inserting a foreign antigen peptide into the molecular surface of a secretory protein, a carrier, having a signal peptide. BCG constituting the present invention secretes a fusion protein to be obtained by inserting a foreign antigen peptide into the molecular surface of an .alpha.-antigen derived from mycobacteria. Said fusion protein has significantly increased antigenicity and immunogenicity. Therefore, when it is inoculated into animals, it is efficiently recognized by B cells which recognize said antigen, thereby effectively inducing the production of an antibody to said antigen. When said BCG itself is inoculated into animals, it continuously secretes said fusion protein in the bodies of the animals while continuously propagating therein. Therefore, said BCG is an extremely useful vaccine.

Abstract: A diagnostic reagent for hepatitis C, which detects an antibody induced by infection of hepatitis C virus, and comprises the second envelope protein or first non-structural protein which is encoded by the gene of hepatitis C virus and has a sugar chain. This invention also provide a method for detecting an anti-hepatitis C virus antibody. The use of the diagnostic reagent for hepatitis C according to the present invention makes highly sensitive diagnosis of hepatitis C possible.

Abstract: A diagnostic reagent for hepatitis C, which detects an antibody induced by infection of hepatitis C virus, comprising the second envelope protein or first non-structural protein which is encoded by the gene of hepatitis C virus and has a sugar chain. This invention also provides a method for detecting an anti-hepatitis C virus antibody. The use of the diagnostic reagent for hepatitis C according to the present invention makes highly sensitive diagnosis of hepatitis C possible.

Abstract: The antigenic peptide represented by the following amino acid sequence (SEQ ID NO: 1) ##STR1## and a method of the detection of anti-HCV antibodies wherein the above peptide is brought into contact with a sample under the conditions that the peptide is bound to anti-HCV antibodies present in the sample to form an immunological complex and the formation of the immunological complex is measured to confirm the existence of the anti HCV antibodies in the sample. The method is highly specific and sensitive to anti-HCV antibodies.