Kim Eun, Khan Muhammad S, Shin Juyeop, Huang Shaohua, Ferrari Alessandro, Han Donghoon, An Eunjin, Kenniston Thomas W, Cassaniti Irene, Baldanti Fausto, Jeong Dohyeon, Gambotto Andrea
Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Department of Infectious Diseases and Microbiology, University of Pittsburgh School of Public Health, Pittsburgh, Pennsylvania, USA.
bioRxiv. 2024 Oct 25:2024.10.25.620289. doi: 10.1101/2024.10.25.620289.
COVID-19 vaccines effectively prevent symptomatic infection and severe disease, including hospitalization and death. However, unequal vaccine distribution during the pandemic, especially in low- and middle-income countries, has led to the emergence of vaccine-resistant strains. This underscores the need for alternative, safe, and thermostable vaccine platforms, such as dissolved microneedle array patches (MAP) delivering a subunit vaccine, which eliminate the need for cold chain and trained healthcare personnel. This study demonstrates that the SARS-CoV-2 S1 monomer with RS09, a TLR-4 agonist peptide, serves as an optimal protein subunit immunogen. This combination stimulates a stronger S1-specific immune response, resulting in binding to the membrane-bound spike on the cell surface and ACE2-binding inhibition, compared to the monomer S1 alone or trimer S1, regardless of RS09. MAP delivery of the rS1RS09 subunit vaccine elicited higher and longer-lasting immunity compared to conventional intramuscular injection. S1-specific IgG levels remained significantly elevated for up to 70 weeks post-administration. Additionally, different doses of 5, 15, and 45 g of MAP vaccines induced robust and sustained Th2-prevalent immune responses, suggesting a dose-sparing effect and inducing significantly high neutralizing antibodies against the Wuhan, Delta, and Omicron variants at 15 and 45 g dose. Moreover, gamma irradiation as a terminal sterilization method did not significantly affect immunogenicity, with irradiated vaccines maintaining comparable efficacy to non-irradiated ones. The stability of MAP vaccines was evaluated after long-term storage at room temperature and refrigeration for 19 months, showing minimal protein degradation. Further, after an additional one-month of storage at elevated temperature (42°C), rS1RS09 in both non-irradiated and irradiated MAP degraded less than 3%, while the liquid subunit vaccine degraded over 23%. Overall, these results indicate that gamma irradiation sterilized MAP-rS1RS09 vaccines maintain stability during extended storage without refrigeration, supporting their potential for mass production and widespread use in global vaccination efforts.
新冠病毒疫苗能有效预防有症状感染和严重疾病，包括住院和死亡。然而，疫情期间疫苗分配不均，尤其是在低收入和中等收入国家，导致了疫苗抗性毒株的出现。这凸显了对替代的、安全的和热稳定疫苗平台的需求，比如递送亚单位疫苗的溶解微针阵列贴片（MAP），其无需冷链和专业医护人员。本研究表明，带有TLR-4激动剂肽RS09的新冠病毒S1单体可作为最佳蛋白质亚单位免疫原。与单独的单体S1或三聚体S1相比，无论有无RS09，这种组合都能刺激更强的S1特异性免疫反应，从而与细胞表面的膜结合刺突结合并抑制ACE2结合。与传统肌肉注射相比，rS1RS09亚单位疫苗的MAP递送引发了更高且更持久的免疫力。给药后长达70周，S1特异性IgG水平仍显著升高。此外，5、15和45微克的不同剂量MAP疫苗诱导了强大且持续的以Th2为主的免疫反应，表明有剂量节省效应，并在15微克和45微克剂量时诱导出针对武汉、德尔塔和奥密克戎变体的显著高水平中和抗体。此外，γ射线辐照作为一种终端灭菌方法，对免疫原性没有显著影响，辐照后的疫苗与未辐照的疫苗保持相当的效力。在室温下长期储存19个月以及冷藏后，对MAP疫苗的稳定性进行了评估，结果显示蛋白质降解极少。此外，在高温（42°C）下再储存一个月后，未辐照和辐照的MAP中的rS1RS09降解均不到3%，而液体亚单位疫苗降解超过23%。总体而言，这些结果表明，γ射线辐照灭菌的MAP-rS1RS09疫苗在无冷藏的长期储存过程中保持稳定，支持了它们在全球疫苗接种工作中大规模生产和广泛使用的潜力。
