A QS21+ CpG-Adjuvanted Rabies Virus G Subunit Vaccine Elicits Superior Humoral and Moderate Cellular Immunity

Background: Rabies remains a fatal zoonotic disease caused by rabies virus (RABV), posing substantial global health challenges. Current vaccine production faces challenges in manufacturing efficiency and cost-effectiveness. The RABV glycoprotein (RABV-G) serves as the key antigen for eliciting protective immunity. Methods: We developed a novel QS21+CpG-adjuvanted RABV-G subunit vaccine and systematically compared its performance against three control formulations: mRNA vaccine composed of H270P-targeted mutation packaged in lipid nanoparticles (LNP), named LNP-mRNA-G-H270P, commercial inactivated vaccine, and alum-adjuvanted RABV-G subunit vaccine. Results: The result show that the G+QS21+CpG subunit vaccine elicited superior humoral immunity, as evidenced by significantly higher RABV-G-specific IgG titers and virus-neutralizing antibody responses compared to all other groups. The LNP-mRNA-G-H270P vaccine maintained its expected cellular immunity advantage, with the G+QS21+CpG group exhibiting moderately reduced but still significant levels of IFN-γ-secreting splenocytes and levels of IL-2 in the supernatant of spleen cells, as well as IFN-γ-producing CD4+ T cells. Both LNP-mRNA-G-H270P and G+QS21+CpG vaccine groups provided 100% protection against lethal challenge (50LD50 RABV). Conclusions: These findings provide novel vaccine/adjuvant strategies for rabies while elucidating platform-specific immunogenicity patterns, offering critical insights for pathogens requiring balanced humoral/cellular immunity.