ANTIDIGOXIN SCFV FRAGMENTS EXPRESSED IN BACTERIA AND IN INSECT CELLS HAVE DIFFERENT ANTIGEN-BINDING PROPERTIES

A gene encoding a single-chain antibody fragment directed against digo xin (named 1C10 scFv) was cloned in two expression systems, For this p urpose, a new baculovirus transfer cassette fully compatible with the procaryotic pHEN vector was constructed, Baculovirus production led to higher yield than did Escherichia coli expression. The procaryotic fr agment showed variations in the fine specificity profile but an affini ty constant nearly identical to that of the 1C10 F-ab, whereas the euc aryotic scFv fragment had a lower affinity with a specificity profile identical to original mAb, The half-lives of the digoxin:scFv complexe s and the global specificity are compatible with therapeutic use of th is antibody fragment. (C) 1998 Federation of European Biochemical Soci eties.