MODULATING THE IMMUNOLOGICAL PROPERTIES OF A LINEAR B-CELL EPITOPE BYINSERTION INTO PERMISSIVE SITES OF THE MALE PROTEIN

In a previous study, a set of positions in the MalE protein from Esche richia coli were identified, which tolerated short insertions or delet ions without compromising the maltose binding activity of the protein. It is now shown that these sites accommodate an insert of 13 amino ac ids and are, therefore, permissive. Eleven sites were used, including eight permissive sites, to display a linear neutralization B-cell epit ope of poliovirus (C3 epitope) at different positions on the surface o f MalE. The affinity of a monoclonal neutralizing anti-poliovirus anti body (anti-C3 mAb) for the hybrid proteins varied from undetectable, t o more than 1000 times higher than for the synthetic peptide. Therefor e, some MalEC3 proteins mimic interactions of the viral epitope with t he monoclonal antibody more efficiently than the free peptide. The res ults are interpreted in terms of the mobility of the insert and its fl anking regions. It was further shown that some of the purified hybrid proteins are able to induce high titer anti-C3-peptide antibodies in m ice. A strong correlation exists between the capacity of a MalEC3 prot ein to induce anti-C3-peptide antibodies and the antigenicity of the i nserted peptide, measured with a polyclonal serum raised against the s ynthetic peptide. (C) 1997 Elsevier Science Ltd.