Comparison of enzyme-labelled F(ab')2 and IgG conjugates in an enzyme-immunoassay for hepatitis B 'e' antigen

An improved enzyme-immunoassay (EIA) for the detection of hepatitis B 'e' antigen (HBeAg) and its corresponding antibody is described. The present test is as sensitive as the previous one but it is more specific as demonstrated by testing donor/recipient sera, donor plasmas and patients sera. Interference by antibody against hepatitis B surface antigen (HBsAg) did not occur due to the use of HBsAg-free reagents. Interference by rheumatoid factor could be avoided by using enzyme-labelled F(ab')2 rather than IgG conjugates. The application of an F(ab')2 conjugate, however, introduced other non-specific reactions, particularly in sera from patients with (autoimmune) liver disorder. Further study into the applicability of F(ab')2 conjugates is therefore indicated.