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Abstract A two-step direct radioimmune test was used to detect hepatitis B virus associated antigen in human serum or plasma. The procedure involved the use of polypropylene tubes coated with hyperimmune guinea pig serum, and 125I-labeled specific hepatitis B virus antigen immune globulin. The technique appeared to be more sensitive than other immunologic assays, including indirect radioimmune methods based on competition of unlabeled antigen with 125I-labeled antigen. Various blood donor populations were tested for antigen by the direct radioimmune test, by complement fixation, agar gel diffusion and counterimmunoelectrophoresis. The increased sensitivity of the radioimmune procedure resulted in the detection of about 3 to 8 times as many positive sera as the above three immunologic methods. The percentages of positive sera by radioimmune assay were: about 1% in volunteer blood donors, about 2% in commercial blood donors and about 40% in hepatitis-implicated patients.
Ling et al. (1972) studied this question.