MBP(85-99), an immuno-dominant epitope of myelin basic protein which binds to the major histocompatibility complex haplotype HLA-DR2 is widely implicated in the pathogenesis of multiple sclerosis. J5, an antagonist of MBP(85-99), that blocks the binding of MBP(85-99) to soluble HLA-DR2b much more efficiently than glatiramer acetate (a random copolymer comprising major MHC and T-cell receptor contact residues), was transformed into analogs with superior biological half-lives and antagonistic-activities by substitution of some of its residues with homo-β-amino acids. S18, the best analog obtained ameliorated symptoms of experimental autoimmune encephalomyelitis at least twice more effectively than glatiramer acetate or J5. S18 displayed marked resistance to proteolysis in-vitro; biological impact of which was evident in the form of delayed clinical onset of disease and prolonged therapeutic-benefits. Besides active suppression of MBP(85-99)-reactive CD4(+) T-cells in-vitro and in-vivo S18 treatment also generated IL-4 producing CD4(+) T-cell clones, through which protective effect could be transferred passively.