PURPOSE: To make nucleic acid related to hepatitis of non-A non-B type or antigen protein for diagnosis, prevention and treatment of hepatitis of non-A non-B type or antigen protein by isolating ana purifying nucleic acid related to hepatitis of non-A non-B type or antigen protein and using as a diagnosticum and an immunogen.

CONSTITUTION: Human serum which has been known to be transfused to human and then to cause hepatitis of non-A non-B type was inoculated into vein of chimpanzee and hepatitis is caused. The hepatitis is not observed to have antibody antigen system specific to hepatitis B virus and hepatitis A virus but change in ultrafine structure specific to hepatitis of non-A non-B type has been observed in cytoplasm in liver cell. Nucleic acid was extracted from plasma of the chimpanzee. The genome RNA is shown by formula I and antigen protein of hepatitis virus of non-A non-B type is found to have an amino acid sequence shown by formula II.