High-Resolution Epitope Mapping For Monoclonal Antibodies To The Structural Protein E-Rns Of Classical Swine Fever Virus Using Peptide Array And Random Peptide Phage Display Approaches

The structural glycoprotein E-rns (an envelope protein with RNase activity) of classical swine fever virus (CSFV) IS not well characterized with respect to its antigenic structure and organization Here, we investigated the antigenic sites on E-rns by raising mAbs against the Escherichia coli expressed Ens of CSFV strain Alfort/187 and defined the B-cell epitopes recognized by these antibodies Eighteen mAbs to E-rns were identified and they were classified as either immunoglobulin subclass G1 or G2b Using an array of overlapping 12-mer peptides, spanning aa 27-227 of E-rns the epitopes for 12 mAbs were mapped to a high resolution of six to eight residues which cluster in five discrete locations, (31)GIWPEKIC(38) (group I), (NYTCCKLO72)-N-65 (group II), (127)QARNRPTT(134) (group III), (145)SFAGTVIE(152) (group IV) and (VEDILY166)-V-161 (group V) Two mAbs recognize two or more antigenic determinants, including the group II epitope The epitopes for four other mAbs could not be mapped using the overlapping 12-mer peptides Random peptide phage display with one mAb from each of all the groups except group V further identified some conserved residues that may be critical for binding antibodies, i e Trp(33) in the epitope of group I Leu(71) in the epitope of group II, Gln(127) and Apn(133) in the epitope of group Ill, and Ser(145) and Gly(148) in the epitope of group IV This study has provided new insights into the structure and organization of epitopes on the CSFV E-rns and valuable epitope information for the rational design of vaccines drugs and diagnostic immunoassays for CSFV