IMMUNORECOGNITION OF RING SKELETON OF TAXANES BY CHICKEN EGG-YOLK ANTIBODIES

Anti-10 deacetylbaccatin III (DAB) antibodies (IgY) were elicited in h ens immunized with a succinyl-DAB/BSA conjugate and extracted from egg yolk. As shown by indirect competitive inhibition enzyme immunoassay (CIEIA), the addition of free-DAB competitively inhibited the binding of affinity purified anti-DAB IgY to DAB/BSA solid phase conjugated an tigen. The assay enabled the detection of DAB in concentrations as low as 7.5 ng/ml (13.7 nM DAB), whereas anti-DAB IgY did not react with t axol even at a concentration a thousand times higher. The structural r equirements of the diterpenoid nucleus for binding to IgY were conside red on the basis of the levels of cross-reaction found with 10 authent ic taxanes. The results indicate that anti-DAB IgY represents the firs t high affinity antibody produced capable of recognizing the ring skel eton of taxol precursors.