Analysis of antigenic structure of Potato Virus M Ukrainian strains

Abstract

The antigenic structure of two Ukrainian strains VI and U7 of Potato Virus M (PVM) was studied by using three mouse monoclonal antibodies (MAbs). Tryptic fragments of PVM coat protein (CP) 22 Glu-Lys 35 and 22 Gly-Lys 35 were found to be recognised by two MAbs, M6D5 and M9GL The amino acid substitution Glu-* Gly at the position 22 of PVM U7 coat protein did not affect antibody binding to both tryptic fragments and PVM CP. Mab M9G1 interfered with MAb M4C1 in dot immunobinding assay. Synthetic peptide P14, corresponding to tryptic fragment 22 Glu-Lys 35 , inhibited the interaction of MAb M6D5 with CP and peptide P14 more effectively than that of MAb M9GJ. The modification of the side chain positive charge of Lys 35 to negative one in tryptic peptides 22 Glu-Lys 35 and 22 Gly-Lys 35 using citraconic anhydride resulted in a twofold increase of the reaction of MAb M9G1 and slightly reduce the interaction of MAb M6D5 with both fragments. On the basis of these results, it was concluded that three PVM-specific epitopes are located at the N-terminal region and form original immunogenic site of PVM coat protein. MAbs M6D5 and M9GJ recognise sequentially overlapping epitopes and the common site for both epitopes is presented in the fragment 22 Glu/Gly-Lys 3S. MAbs M4C1 and M9G1 recognise either overlapping, or conformational approximated epitopes.