Nanovaccines co-delivering antigen and dual TLR agonists potentiate aged immunity by orchestrating TCR repertoire

Immunosenescence increases susceptibility to varicella-zoster virus (VZV) infection in the elderly while compromising vaccine responsiveness. Although clinical adjuvants such as AS01 have improved vaccine efficacy, challenges associated with saponin-based components and separate antigen-adjuvant formulations persist. Here, we developed a nanovaccine, NP(gEIM), that co-encapsulates VZV glycoprotein E (gE) with the TLR4 agonist MPLA and TLR7/8 agonist IMQ in lipid nanoparticles via flash nanocomplexation (FNC), enabling coordinated co-delivery of antigen and adjuvants. NP(gEIM) efficiently targeted draining lymph nodes and promoted antigen-presenting cell uptake and maturation. In young and aged mice, NP(gEIM) elicited gE-specific antibody responses and Th1-biased cellular immunity comparable to AS01-adjuvanted gE vaccines while exceeding aluminum-adjuvanted vaccines. Moreover, NP(gEIM) enhanced IFN-γ and TNF-α production by antigen-specific CD4⁺ and CD8⁺ T cells while reducing immunosuppressive Treg and MDSC populations in aged mice. Notably, NP(gEIM) reshaped the TCR repertoire by promoting selective expansion of putative antigen-responsive T cell clones and altering TCR V/J gene usage and CDR3 length distribution, providing molecular insights into vaccine-induced T cell responses. Collectively, this study presents a nanovaccine strategy enabling coordinated delivery of antigen and dual TLR agonists. By integrating humoral and cellular immunity with TCR repertoire modulation, NP(gEIM) offers a potential strategy for improving vaccine responses in aging populations and developing vaccines against age-associated infectious diseases.