Application of the technology developed in the study of hepatitis A and B and the use of the chimpanzee model for NANB hepatitis represents only a rudimentary beginning in the development of specific serologic tests to eliminate the blood of those donors who transmit NANB hepatitis to recipients. Develop a more sensitive method capable of detecting all infectious blood, such as radioimmunoassay or enzyme linked immunosorbent assay and must be shown to have specificity and predictive value. If this is to be accomplished, the patterns of antigen and antibody production must be better delineated. Using this type of approach, the major thrust of the offeror's efforts is to identify virus particles and viral antigens associated with NANB hepatitis and to develop simple, practical assays for detection of virus antigen andantibody.