Direct solid-phase radioimmunoassay (dSP-RIA) for detection of antibody to hepatitis B surface (HBs) antigen.

Using direct solid-phase radioimmunoassay (dSP-RIA) which was shown to be specific and about 10000 times more sensitive than immunodiffusion and even 10 times more sensitive than the radioimmunoprecipitation test used by us before, anti-HBs was detected in 90% of hepatitis B convalescents who were followed up for a one year observation period and who had eliminated HBs antigen from their sera (60/68). In 13% of these patients (8/60 anti-HBs was only temporarily detectable. In 50% of all patients who developed antibody within a two to twelve months observation period (n = 151), anti-HBs appeared within three to four months after height of disease. In 16.5% of patients with HBs antigen negative hepatitis (32/193) anti-HBs was observed to develop during convalescence indicating a type B infection despite a negative finding for HBs antigen in the acute stage of disease. Using dSP-RIA anti-HBs was found in 5.5% of voluntary blood donors (n = 1036), in 20.2% of hospitalized patients without clinical hepatitis (n = 252), and in 30.6% of hospital staff (n = 304). Anti-HBs increases with age: in 14 year olds we found 0.5%, in 60 year olds, 14%. The fact that at least 70% of the anti-HBs positive normal persons and medical staff groups had no history of hepatitis illustrates the frequency and importance of subclinical hepatitis B infections.