Assessment of IgG avidity against pertussis toxin and filamentous hemagglutinin via an adapted enzyme-linked immunosorbent assay (ELISA) using ammonium thiocyanate

► IgG-anti-PT or -FHA antigen-antibody binding is not affected by urea. ► Ammonium thiocyanate NH4SCN disrupts IgG-anti-PT or -FHA antigen-antibody binding. ► IgG-anti-PT and -FHA antibody avidities are affected by time of incubation. ► IgG-anti-PT and -FHA antibody avidities are affected by temperature. ► IgG-anti-PT and -FHA antibody avidities are independent of antibody concentrations.