An immunofluorescence blocking test to detect antibodies against the hepatitis B delta and core (HBcAg) antigens

An immunofluorescence (IFL) blocking test has been developed to detect antibodies against the hepatitis B delta and core (HBcAg) antigens. The test proved useful to overcome the difficulties inherent in the detection of anti-delta by standard direct and indirect IFL procedures and provided a simple alternative to detect anti-HBc whenever serological techniques or indirect IFL, requiring purification of Dane particle cores or rare and selected HBcAg positive substrates, cannot be accomplished. The blocking test proved reliable and specific; though less sensitive than standard IFL techniques, it is simple and valuable in routine serological screening for anti-delta and anti-HBc.