Deconstructing the antigenic profile of a protective epitope from measles virus fusion protein using overlapping peptides

Abstract

Three different approaches of using overlapping peptides have been compared to analyse the fine specificity of the antibody response to a protective epitope from measles virus (MV) fusion protein, spanning residues 397–420. Anti-peptide antibodies raised in BALB/c, CBA and C57BL/6 mice were shown to react with the homologous peptide and the MV by ELISA. Results from indirect ELISA using 15mer peptides (overlapping by one residue) as solid phase antigens have shown that anti-peptide antibodies from CBA and C57BL/6 mice recognised the same B-cell epitope(s) located within the 398–414 region, whereas BALB/c mice predominantly recognised epitopes located within the 400–417 region. When the 15mer peptides were used as fluid phase antigens in an inhibition ELISA, peptide 405–419 was shown to be the most effective inhibitor in all three strains of mice. Analysis of serum samples by SPOTs ELISA has shown that the region 407–417 was predominantly recognised by BALB/c mice, whereas antibodies from C57BL/6 mice recognised the 408–420 region. No reactivity was observed with serum samples from CBA mice. Although the majority of the identified B-cell epitopes were shown to overlap by the three methods, the identified boundaries of these epitopes differed, suggesting that the size and the mode of peptide presentation affects their antigenicity.