The location of biologically relevant epitopes on recombinant human β interferon in which Ser-17 replaces Cys-17 (rh[Ser17]IFN-β) was evaluated by testing the immunoreactivity of antibodies against 159 sequential, overlapping octamer peptides. Three monoclonal antibodies (mAbs) that neutralize rh[Ser17]IFN-β biologic activity, designated A1, A5, and A7, bound to peptides spanning only residues 39-48, whereas nonneutralizing mAb bound less specifically at multiple sites near the amino terminus. The immunoreactivity of peptides spanning residues 40-47 that contained a series of single amino acid substitutions suggested that residues 41-43 (Pro-Glu-Glu) and 46 (Gin) are important for the binding of neutralizing mAbs. The reactivity of mAbs to larger synthetic peptides containing rh[Ser17]IFN-β sequences from residue 32 through residue 56 was evaluated. All mAbs except A7 reacted with synthetic peptides representing rh[Ser17]IFN-β residues 32-47, 40-56, and 32-56, but only mAbs A1 and A5 bound to the core peptide composed of residues 40-47. Peptide 32-56 effectively blocked the binding of mAbs A1 and A5 to rh[Ser17]IFN-β and markedly inhibited their neutralizing activity. Biologic activity of the peptides was undetectable. Rabbit antisera raised against peptides 32-47 and 40-56 recognized rh[Ser17]IFN-β but did not neutralize its antiviral activity. Thus, structure-function analysis by peptide mapping has permitted the identification of a linear epitope recognized by neutralizing antibody on a biologically active cytokine. We conclude that the region spanning residues 32-56 is of major importance in the expression of the biologic activity of human IFN-β.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - 1991|
- Monoclonal antibodies
- Multiple peptide synthesis
ASJC Scopus subject areas