Liposomal Co-Delivery of Antigenic Glycan LDNF and α-GalCer Elicits Potent IgG Responses with Potential for Anti-Helminth Immunity

Introduction: Parasitic worms (helminths) express unique antigenic glycans such as LDN and LDNF, which are absent in mammalian hosts and represent promising vaccine targets. However, free glycans typically elicit weak immune responses and require multivalent delivery and adjuvants to enhance immunogenicity and promote antibody class-switching. Methods: Two cetyl-modified glycan antigens (LDN-C16 and LDNF-C16) were chemo-enzymatically synthesized and incorporated into liposomes, either with or without the invariant natural killer T cell agonist α-GalCer as an adjuvant. C57BL/6 mice were immunized subcutaneously. Humoral immune responses were evaluated by ELISA using glycan-BSA conjugates. Cytokine levels were measured in sera from immunized mice. Additionally, the ability of immune sera to recognize native helminth proteins was assessed by Western blotting using protein extracts from adult Schistosoma japonicum worms. Results: Liposomal delivery of LDNF, but not LDN, induced potent glycan-specific antibody responses. Adding α-GalCer slightly reduced total antibody titers but enhanced response quality by shifting IgM to IgG, increasing IgG1 and decreasing IgG2b. Liposomal LDNF with α-GalCer also boosted in vivo cytokine responses, increasing IL-4 and IL-10 while maintaining IFN-γ. The induced antibodies showed high specificity for LDNF and effective recognition of native schistosome worm proteins. Conclusion: Liposomal presentation of the LDNF epitope strongly enhances immunogenicity. Co-delivery with α-GalCer effectively promotes class-switched IgG responses, modulates cytokine profiles, and improves recognition of native parasite antigens. This liposomal glycan-antigen delivery strategy represents a promising approach for the development of anti-helminth vaccines targeting glycan epitopes. Keywords: helminth glycans, vaccine target, liposome nanoparticles, α-galcer adjuvant, antibody class switching