Effect of serum treatment on pertussis antibody determination by ELISA

Determination of anti-PT and anti-FHA antibodies by ELISA and neutralization titer by CHO-cell method were performed with inactivated and uninactivated human sera. The findings were as follows: in inactivated sera, higher anti-PT ELISA antibody titers were shown compared with the titers determined with corresponding inactivated sera, especially in sera having low ELISA antibody titers; however, anti-FHA ELISA antibody titers remained identical, with the uninactivated or inactivated sera. CHO-cell neutralization titer remained identical and stable between the uninactivated and inactivated sea. CHO-cell neutralization titers correlated with anti-PT ELISA antibody titers in sera without inactivation. Anti-PT ELISA antibody titers in inactivated sera, however, did not correlate with the corresponding CHO-cell neutralization titers. These results suggest the possible existence of (a) substance(s) with affinity to PT which enhance(s) the ELISA reaction when sera are inactivated. Therefore, the inactivation of sera is not favorable for anti-PT determination by ELISA.