The HBV markers and HBV DNA in poultry sera, Yolk and bovine milk whey were detected by reversed passive hemagglutination assay (RPHA), enzymeimmunoassay (EIA) and polymerase chain reaction (PCR).
Based on high specificity of antigen-antibody reaction, enzymeimmunoassay (EIA) identified unknown antigen by antibody labelled with enzyme as standard reagent.