A palmitoyl-tailed sequential oligopeptide carrier for engineering immunogenic conjugates

Abstract The main guideline in designing effective immunogens as vaccine candidates capable of eliciting potent and specific immune responses is to combine B/T cell epitopes and adjuvants as immunostimulators on the same carrier that links the major histocompatibility complex with T cell receptors. Aiming at contributing to the development of carriers for human usage a helicoid type sequential oligopeptide carrier, SOC n -II, formed by the repeating tetrapeptide unit (Aib-Lys-Aib-Gly) n , n  = 2–7, elongated from the amino-terminus by the palmitoyl group, known for its adjuvanticity, is now presented. The main B cell epitope, PPGMRPP, of the Sm autoantigen against which the majority of antibodies in patients with systemic lupus erythematosus is directed, was coupled to the Lys-N ɛ H 2 groups of the carrier in four copies and the resulting conjugate Palm-SOC 4 -II-Sm 4 was subjected to animal immunizations without utilizing any adjuvant. The induced immune response was comparable with that produced when Ac-SOC 4 -II-Sm 4 was administered in animals following the conventional immunization protocol of complete/incomplete Freund's adjuvant. High titers of anti-Palm-SOC 4 -II-Sm 4 antibodies were generated, which recognize the priming immunogenic conjugate, as well as reconstituted Sm mimics but not the carrier alone. It is concluded that Palm-SOC n -II carrier is a valuable tool for engineering immunogens eliciting enhanced and specific humoral immune responses.