THE EFFECT OF FORMALDEHYDE, HYDROGEN-PEROXIDE AND GENETIC DETOXIFICATION OF PERTUSSIS TOXIN ON EPITOPE RECOGNITION BY MURINE MONOCLONAL-ANTIBODIES

The effect of detoxification of pertussis toxin (PT) for vaccine usage by either generic manipulation, hydrogen peroxide or formaldehyde tre atment on epitope recognition by a large collection of murine monoclon al pertussis toxin antibodies (PT MAbs) was assessed in a solid-phase and a soluble phase enzyme-linked immunosorbent assay (ELISA). The MAb binding patterns were found to be different in the two assays as the immobilization step appeared to cause conformational alterations in th e native as well as the toxoided forms of PT According to the solid-ph ase ELISA, genetic, hydrogen peroxide and 0.35% formaldehyde detoxific ation of PT resulted in reduced epitope binding in 2.9, 31.4 and 78.1% of the MAbs, respectively In the soluble-phase ELISA, in which the MA bs were allowed to react with the toxoids or native toxin in solution, the percentages of MAbs showing decreased binding activity were 9.1, 50.0 and 71.4%, respectively. Stabilization of native PT and the genet ically inactivated PT by 0.035% formaldehyde reduced the epitope bindi ng activity in 50.0 and 8.7% of the MAbs, respectively. Increased anti body binding in the soluble-phase ELISA was observed in some of the to xoids: this ranged from 0% in the 0.35% formaldehyde-treated PT to 13. 6% in the hydrogen peroxide-treated and 27.3% in the genetically detox ified PT. Regarding the effects of detoxification on epitopes recogniz ed by PT-neutralizing MAbs in the soluble-phase ELISA, we found that t reatment of PT with either 0.035%, 0.35% formaldehyde or hydrogen pero xide induced impairment of epitope binding in 72.7, 81.8 and 45.5% of the MAbs, respectively. In the genetically inactivated PT, the epitope s recognized by the neutralizing MAbs either appeared to remain intact or to show increased MAb binding activity. The epitope-binding patter ns of several PT MAbs with mouse-protective properties varied consider ably and were shown to be dependent out the detoxification procedure e mployed. The relevance of epitope alterations on PT as a vaccine compo nent is discussed The results of the present study may have important implications for future quality assessment of PT for use in acellular pertussis vaccines. Copyright (C) 1996 Elsevier Science Ltd