MOLECULAR APPROACH TO FIND TARGET(S) FOR OLIGOCLONAL BANDS IN MULTIPLE-SCLEROSIS

Objectives-Oligoclonal bands are a characteristic finding in the CSF o f patients with multiple sclerosis, yet their target antigen(s) remain unknown. The objective was to determine whether a filamentous phage p eptide library could be employed to allow the oligoclonal bands to sel ect their own target epitopes. Methods-CSF IgG antibody from 14 patien ts with multiple sclerosis and 14 controls was used to select individu al phage clones from a bacteriophage library containing=4 x 10(7) diff erent hexamers expressed on its surface pIII protein. The amino acid s equence selected was deduced by sequencing the DNA of the genetically engineered insert. Results-In general, after three rounds of selection , CSF from both patients with multiple sclerosis and controls selected one to two consistent peptide motifs. Five out of 14 patients with mu ltiple sclerosis, and one control, selected the amino acid sequence mo tif, RRPFF. Given 20 possible amino acids per position, the likelihood of five patients selecting the same linear five amino acid sequence i s at most 1.6 x 10(-13), corrected for the number of clones sequenced. A GenBank computer search showed that this sequence is found in the E pstein-Barr Virus nuclear antigen (EBNA-1), and a heat shock protein a lpha B crystallin. Human serum antibodies to a synthetic peptide conta ining RRPFF were virtually exclusively found in patients with prior in fection by Epstein-Barr virus. Other studies have suggested a relation between Epstein-Barr virus infection and multiple sclerosis, includin g nearly 100% Epstein-Barr virus seropositivity among patients with mu ltiple sclerosis and increased concentrations of antibody to EBNA in C SF of patients with multiple Gainesville, Florida sclerosis. By antige n specific immunoblotting, antibodies to the RRPFF motif in the CSF we re shown to correspond to a subset of oligoclonal bands in the CSF fro m the same patient. Conclusion-This study shows that phage epitope dis play libraries may be used to select amino acid motifs which are poten tially relevant to the pathogenesis of multiple sclerosis.