Supramolecular complex glycoconjugate vaccine generates self-enhancement effects for carbohydrate antigen delivery

Targeting delivery of tumor-associated carbohydrate antigen (TACA)-based vaccine to antigen-presenting cells (APCs) mediated by endogenous antibodies can improve the immunogenicity of TACA. However, an essential requirement of this approach is to generate high titers of endogenous antibodies in vivo through pre-immunization, which complicates the immunization procedure and may cause side effects. Herein, we report a new generation of APC-targeting TACA-based supramolecular complex vaccine, assembled by sialyl Thomsen-nouveau-bovine serum albumin-adamantine (sTn-BSA-Ada) and heptavalent rhamnose (Rha)-modified β-cyclodextrin (β-CD) via host–guest interaction. The complex vaccine retained anti-Rha antibodies recruiting capability and facilitated the APCs uptake of the vaccine via the interaction of the Fc-domain with the Fc receptors on APCs. We demonstrate that direct immunization of complex vaccine elicited anti-Rha and anti-sTn specific immune response synchronously, generating a novel self-enhancement effect that can improve the antigen delivery to APCs in high efficacy. The structure–activity relationship (SAR) study proved that complex vaccine 4 with polyethylene glycol 6 (PEG6) linker in host molecule provoked a robust and specific sTn immune response comparable to the pre-immunization approach. The antisera induced by complex vaccine, either through direct immunization or pre-immunization, exhibited equal potency of cytotoxicity against the sTn expression cancer cells. This study provides a general platform for TACA-based vaccines with self-enhancement effects without the need for pre-immunization.