Determination of binding site of anti-tumour necrosis factor-alpha monoclonal antibody using hybrid and mutant proteins.

In order to map the immunogenic epitope for the monoclonal antibody E7H2 on the human tumour necrosis factor (hTNF-alpha) molecule, a number of chimeric proteins were developed by in-frame joining segments of the human genes encoding TNF-alpha and lymphotoxin (TNF-beta) as well as by coupling appropriate coding regions for human and mouse TNF-alpha. High level expression of these chimeric genes was achieved in Escherichia coli by placing the coding sequences under control of either E. coli trp-promoter or a tandem of bacteriophage T7 constitutive promoters A2 and A3. As revealed by Western blot analysis with monoclonal antibody E7H2 directed against human TNF-alpha, the region involved in the binding of this antibody includes sequence ValGluLeuArg in the N-terminal part of the TNF-alpha molecule.