Design and Immunogenicity of a Quadrivalent mRNA Vaccine Targeting HSV-2 with Comparative Evaluation of Co-formulated and Admixed Formulations

Youngran Cho¹Chanwoo Lee²Sang-In Park³Yeongjun Kim²Yu-Sun Lee¹Seonghyun Lee¹Subin Yoon¹Gahyun Roh¹Dahyeon Haa¹Ayoung Oh¹Kyusang Cho¹Jisun Lee¹Hyo-Jung Park¹Hye-Ra Lee²Jae-Hwan Nam^1*

• ¹The Catholic University of Korea - Songsim Campus, Bucheon-si, Republic of Korea
• ²Korea University - Sejong Campus, Sejong, Republic of Korea
• ³Daegu Haany University, Gyeongsan-si, Republic of Korea

The globally prevalent herpes simplex virus 2 (HSV-2) establishes lifelong latent infections in sensory neurons and causes recurrent genital disease. However, no vaccine is available to prevent HSV-2 infection. The mRNA vaccine platform offers distinct advantages over protein-based approaches, including rapid antigen design, scalable production, and efficient intracellular expression. We developed a prophylactic quadrivalent mRNA vaccine encoding full-length HSV-2 glycoprotein B (gB2), C (gC2), D (gD2), and E (gE2) and evaluated its immunogenicity and protective efficacy in a murine intravaginal challenge model. Quadrivalent mRNA vaccine-immunized mice showed robust HSV-2-specific immune responses, including high titers of neutralizing antibodies and strong T cell responses, which persisted for at least 16 weeks. Upon viral challenge, vaccinated animals were fully protected from genital disease and exhibited significantly reduced viral copy numbers in the genital tract. Vaccination also inhibited the establishment of latent infections in the dorsal root ganglia, as evidenced by markedly lower HSV-2 DNA levels than those in mock-vaccinated controls. Comparative analysis showed no significant difference between co-formulated and admixed lipid nanoparticle formulations, indicating flexibility in vaccine manufacturing without compromising efficacy. These findings indicate that the quadrivalent mRNA vaccine provides strong and durable protection against both primary and latent infection, supporting its potential as a promising candidate for the prevention of genital herpes.