Enhanced cellular immunity against varicella-zoster virus by β-sitosterol-substituted lipid nanoparticles in mRNA vaccines.

Herpes zoster (HZ), caused by reactivation of varicella-zoster virus (VZV), imposes a substantial health burden, particularly in immunocompromised individuals. Although current HZ vaccines provide effective protection, the live-attenuated vaccine shows age-dependent and waning efficacy, whereas the recombinant zoster vaccine relies on a complex adjuvant system that may present manufacturing and supply challenges. mRNA vaccines offer a promising alternative for HZ prevention, but their efficacy depends on optimized lipid nanoparticle (LNPs) that protect mRNA and support efficient intracellular delivery. Here, we formulated LNPs for an mRNA encoding VZV glycoprotein E by partially or completely replacing cholesterol with two cholesterol-related sterols, the plant-derived sterol β-sitosterol and the immunomodulatory metabolite dendrogenin A (DDA). We found that high-level DDA substitution (≥50%) impaired both antigen-specific antibody responses and T-cell immunity. By contrast, complete β-sitosterol replacement (100% SS-LNPs) enhanced EGFP reporter signals in vitro and in vivo and produced numerically higher antigen-specific T-cell responses than cholesterol-based LNPs (Chol-LNPs), with significantly increased CD4+ T-cell polyfunctionality. Transcriptomic analysis further showed that the immune signatures induced by 100% SS-LNPs largely overlapped with those induced by Chol-LNPs, without evidence of a distinct inflammatory transcriptional program. Together, these findings identify β-sitosterol substitution as a promising formulation strategy for VZV mRNA-LNP development.