From the crude polyclonal the crossreactive antibodies were extracted by incubation with Sepharose bound human IgA and IgM. Specific antibodies were absorpted by incubation with Sepharose bound human IgG. Specific antibodies were eluted by acidic buffer at pH 2.5 followed by neutralization and dialysis. After repeated binding with immobilized human IgG a minimum of 65% protein bound.
The purified polyclonal was conjugated to horseradish peroxidase according to the periodate method followed by gel filtation and ion exchange chromatography to clear unbound conjugate.