1. Institute of Nano Biomedicine and Engineering, Shanghai Engineering Research Center for Intelligent Instrument for Diagnosis and Therapy, School of Sensing Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
2. National Engineering Research Center for Nanotechnology, 28 East Jiangchuan Road, Shanghai 200241, China.
3. Radiology Department of Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin Second Road, Shanghai 200025, China.
Rationale: Novel vaccine R&D is essential to interrupt the COVID-19 pandemic and other epidemics in the future. Subunit vaccines have received tremendous attention for their low cost and safety. To improve the immunogenicity of subunit vaccines, we developed a novel vaccine adjuvant system.
Methods: Here we rationally designed a CpG 1018 and graphene oxide-based bi-adjuvant system to deliver the Receptor-Binding Domain (RBD) of the SARS-CoV-2 spike protein and obtained the graphene oxide-based complex adjuvant nanovaccine (GCR). Furthermore, we developed a microneedle patch vaccine (MGCR) based on the GCR vaccine.
Results: GCR nanovaccine displayed superb antigen loading and encapsulation efficiency. Two dosages of vaccination of GCR nanovaccine could elicit adequate RBD-specific binding antibody response with 2.14-fold higher IgG titer than Alum adjuvant vaccine. The peptide pools assay demonstrated the robust RBD-specific Type 1 Cellular response induced by the GCR nanovaccine in CD8+ T cells. Furthermore, we prepared an MGCR microneedle patch, which generated a similar RBD-specific binding antibody response to the GCR vaccine, sustained a high antibody level above 16 weeks, and significantly elevated the Tcm proportion in mouse spleen. The MGCR microneedle patch vaccine also could be stably stored at room temperature for several months and administrated without medical staff, which maximizes the vaccine distribution efficiency.
Conclusion: The vaccine system could significantly improve the vaccine distribution rate in low-income areas and offer a potential vaccination approach to fight against the SARS-Cov-2 infection and other pandemics occurred in the future.
Keywords: Receptor-Binding Domain, nanovaccine, microneedle patch, RBD-specific Type 1 cellular response, graphene oxide