Empty lipid nanoparticles (eLNPs) with adjuvant activity induce potent immune responses

BACKGROUND AND PURPOSE: Achieving herd immunity via mass vaccination is recognized as the most effective strategy for curbing the transmission of contagious diseases. Among the various types of vaccines, subunit protein vaccines stand out for their favourable safety profile, proven efficacy and straightforward production processes. The development of next-generation vaccines is currently hindered by the scarcity of adjuvants capable of simultaneously amplifying both humoral and cellular immune responses. EXPERIMENTAL APPROACH: This study identified the physical characteristics of empty lipid nanoparticles (eLNP) using electron microscopy and nanoflow cytometry and evaluated the humoral and cellular immune responses induced by eLNP using enzyme-linked immunosorbent assay, neutralization assay and flow cytometry. KEY RESULTS: The main results demonstrated that, compared to the conventional aluminium-based adjuvant, the eLNP formulation elicited significantly higher neutralizing antibody titres and strong medium- to long-term T-cell response. Moreover, the study observed that the proliferation of follicular helper T cells were increased, elevated germinal centre response and durable memory response. CONCLUSION AND IMPLICATIONS: These results highlight the ability of empty lipid nanoparticles (eLNPs) to significantly enhance both humoral and cellular immune responses and their potential for clinical translation. This suggests that eLNP hold promise as a novel adjuvant for future vaccine development.