Polyclonal antisera from immunized hosts are lipid extracted to improve clarity, salt fractionated, dialyzed against phosphate buffered saline containing sodium azide and freeze-dried. Antisera against whole serums are obtained by immunizing host animals with whole serum. Antisera against whole IgG molecules [i.e. Anti-IgG (H+L)] are recommended for bridging PAP to primary antibodies.-Based on immunoelectrophoresis and/or ELISA, the antibody reacts with peroxidase from horseradish roots. It may cross-react with peroxidase from other sources.