SARS-CoV-2 subunit vaccine adjuvants and their signaling pathways

Vaccines are the agreed upon weapon against the COVID-19 pandemic. This review discusses about COVID-19 subunit vaccines adjuvants and their signaling pathways, which could provide a glimpse into the selection of appropriate adjuvants for prospective vaccine development studies. In the introduction, a brief background about the SARS-CoV-2 pandemic, the vaccine development race and classes of vaccine adjuvants were provided. . The antigen, trial stage, and types of adjuvants were extracted from the included articles and thun assimilated. Finally, the pattern recognition receptors (PRRs), their classes, cognate adjuvants, and potential signaling pathways were comprehended. Adjuvants are unsung heroes of subunit vaccines. The in silico studies are very vital in avoiding several costly trial errors and save much work times. The majority of the (pre)clinical studies are promising. It is encouraging that most of the selected adjuvants are novel. Much emphasis must be paid to the optimal paring of antigen-adjuvant-PRRs for obtaining the desired vaccine effect. A good subunit vaccine/adjuvant is one that has high efficacy, safety, dose sparing, and rapid seroconversion rate and broad spectrum of immune response. In the years to come, COVID-19 adjuvanted subunit vaccines are expected to have superior utility than any other vaccines for various reasons.

疫苗是公认的对抗新型冠状病毒肺炎（COVID-19）大流行的利器。本综述探讨了COVID-19亚单位疫苗佐剂及其信号通路，可为未来疫苗开发研究中合适佐剂的遴选提供参考思路。引言部分简要介绍了严重急性呼吸综合征冠状病毒2型（SARS-CoV-2）大流行、疫苗研发竞赛以及疫苗佐剂的分类。研究人员从纳入的文献中提取抗原、试验阶段以及佐剂类型，并进行了归纳整合。最后，明确了模式识别受体（pattern recognition receptors, PRRs）的类别、同源佐剂以及潜在的信号通路。佐剂是亚单位疫苗中默默无闻的功臣。计算机模拟研究对于规避诸多代价高昂的试验失误、节省大量研发时间至关重要。绝大多数（预）临床研究均展现出良好前景。令人振奋的是，多数入选佐剂均为新型佐剂。为获得理想的疫苗免疫效果，必须重视抗原-佐剂-模式识别受体三者的最优匹配。优质的亚单位疫苗/佐剂应具备高效性、安全性、低剂量使用特性以及快速血清转换率和广谱免疫应答能力。未来，基于多重因素，佐剂化COVID-19亚单位疫苗有望展现出优于其他各类疫苗的应用价值。