Antigenic epitopes of Mycobacterium paratuberculosis protein MAP2694 homologous to T-cell receptor gamma-chain are highly recognized in multiple sclerosis Sardinian patients.

Mycobacterium avium ss. paratuberculosis (MAP) is an intracellular
pathogen recently associated with multiple sclerosis (MS). Aiming to
identify immunodominant epitopes belonging to MS related protein MAP2694
(UniProt accession no. Q73WG6), we investigated the binding activity of
selected peptides against MS Sardinian sera. An overlapping 9-mers
peptide library was synthesized spanning the entire aminoacidic sequence
of the protein. Peripheral blood was collected from 47 MS patients and
42 sex and age matched healthy volunteers and subjected to enzyme-linked
immunosorbent assay (ELISA) in order to investigate the reaction
against the linear peptides generated. Two out of 58 synthetic 9-mers
were strongly recognized by MS patients' antibodies compared to
controls. A competitive inhibition assay demonstrated that these two
epitopes are immunodominant antibody targets within MAP2694 protein, as
sera pre-adsorbed with these peptides were able to significantly block
the antibody reaction to the MAP2694 protein, even if at a lesser extent
than MAP2694 protein itself.