Co‐Delivery of Varicella Zoster Virus gE and gI Dual‐Antigen mRNA Vaccine With CpG‐ODN Elicits Robust Immunity

ABSTRACT Herpes zoster (HZ), caused by reactivation of latent varicella zoster virus (VZV), remains a growing health burden. Developing new HZ vaccines with high efficacy and improved tolerability could address limitations of current vaccines and increase vaccination uptake and completion rates. To identify an optimal antigen design, we systematically evaluated multiple mRNA candidates based on VZV glycoprotein E (gE) and I (gI). In mice, membrane‐localized gE induced the strongest and most durable antibody responses, whereas inclusion of gI markedly enhanced T‐cell responses. Co‐delivery of membrane‐localized gE and gI (gE+gI Lmix) elicited the most robust cellular responses, outperforming both single‐antigen and fusion constructs. We therefore selected gE+gI Lmix for further optimization with CpG oligodeoxynucleotide (CpG‐ODN) adjuvants. In both naïve and VZV‐primed mice, CpG‐ODN 1018 increased neutralizing antibody titers and significantly enhanced antigen‐specific CD4 + and CD8 + IFN‐γ + T‐cell responses, with a Th1‐biased profile. The resulting humoral and cellular responses matched or exceeded those induced by Shingrix in mice. Safety assessments revealed no distinct systemic toxicity or histopathological abnormalities following CpG‐ODN 1018 administration. Together, these findings identify dual‐antigen gE/gI mRNA vaccination, particularly in combination with CpG‐ODN 1018, as a promising strategy for HZ prevention, with enhanced cellular immunogenicity and an acceptable preclinical safety profile.