Sequential Oligopeptides Carriers(SOC_n)of immunogenic peptides with a built-in vaccine adjuvant-Application to reconstituted models of AChR,La/SSB and Sm autoantigens

摘要

Among various strategies for producing potent antigens and immunogens,the one using synthetic peptides is perhaps the most appealing,both in conceptual simplicity and in practical convenience.For immunization purpose,peptides(antigenic determinats)have to be covalently conjugated to a protein or an artificial carrier.A novel class of carriers termed Sequential Oligopeptide Carriers(SOC_n)is successfully applied in our laboratory.SOC_n is formed by the(Lys-Aib-Gly)_n sequential motif,where n=2-7,and adopts a predetermined secondary structure of 3_(10)-helix.A new generation of adjuvant-congugated-SOC_n is now presented,with the aim to improve the SOC_n carrier for human usage and avoid the use of complete and incomplete Freund's adjuvant.Interleukin 1(IL-1)is a family of cytokines of key importance in the mechanisms of host defense because of its pivotal role in the onset and development of both immune and inflammatory reactions.To exploit the adjuvant capacity of IL-1,the analysis of the IL-1 beta structure-function relationship has led to the identification of domains selectively endowed with different biological activities.One of this domains,located between the fourth and fifth beta-stands of the IL-1 beta structure(amino acids VQGEESNDK,in position 163-171 in pro-IL-1 beta sequence)shows excellent immunostimulatory and adjuvant effects in vitro and in vivo in the absence of inflammatory and toxic effects.Tetanus toxoid-specific T cell clones were isolated from human donor.To determine the T cell epitopes recognized by the clones,30 peptides representing amphipathic alpha helical regions of the tetanus toxin(TT)were screened for ability to induce proliferation of the clones.Two epitopes were identified.Further investigation of two epitopes showed that the epitope was only seven amino acids in length and had a very hydrophobic sequence,namely YSYFPSV.The ability of this peptide to interact with many different HLA alleles means they may potentially be very useful as"universal carrier molecules"in synthetic vaccines.Aiming at contributing to the development of a carrier that could help to augment and improve the character and the quality of the humoral and cellular immune response,the SOC_n carrier was elongated from the amino-terminus by interleukin-1 beta(IL-1 beta)fragment VQGEESNDK(163-171)as adjuvant.A"promiscuous"T cell epitope deriving from TT,YSYFPSV(593-599),was also covalently attached to the carbocyl-terminus of SOC_n as universal immunogen.