Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran.
Protein Research Center, Shahid Beheshti University, Tehran, Iran.
Virus Res. 2023 Mar;326:199047. doi: 10.1016/j.virusres.2023.199047. Epub 2023 Jan 21.
The receptor binding domain (RBD) plays a pivotal role in the viral entry as it enables the engagement of severe acute respiratory syndrome 2 (SARS-CoV-2) with the human angiotensin-converting enzyme 2 (ACE2) receptor for host cell entry. RBD is the major target for developing viral inhibitors and vaccines. Expression of recombinant RBD in E.coli is highly scalable with a low-cost procedure despite its high expression level compared to expression in mammalian and yeast cells. Using an alternative natural adjuvant system instead of alum adjuvant, increased immunogenicity of RBD antigen in serological assay including direct ELISA and surrogate Virus Neutralization Test (sVNT) was demonstrated with high levels of IgGs and neutralizing antibodies in mice sera immunized with RBD:AlSa (Alum and Sodium alginate) formulation. The sVNT is a simple and fast test that can be used instead of the conventional virus neutralization test requiring live virus and BSL3 laboratory to detect total neutralizing antibodies against RBD. Additionally, results showed a safety profile for sodium alginate which supported using it as an alternative natural adjuvant.
受体结合域（RBD）在病毒进入中起着关键作用，因为它使严重急性呼吸系统综合征 2 型（SARS-CoV-2）能够与人类血管紧张素转换酶 2（ACE2）受体结合，从而进入宿主细胞。RBD 是开发病毒抑制剂和疫苗的主要靶点。尽管与在哺乳动物和酵母细胞中的表达相比，其表达水平很高，但在大肠杆菌中表达重组 RBD 具有高度可扩展性，且成本低廉。使用替代的天然佐剂系统而不是明矾佐剂，在使用 RBD：AlSa（明矾和海藻酸钠）制剂免疫的小鼠血清中，直接 ELISA 和替代病毒中和试验（sVNT）等血清学检测中，RBD 抗原的免疫原性得到了提高，IgG 和中和抗体水平均较高。sVNT 是一种简单快速的试验，可以替代需要使用活病毒和 BSL3 实验室的传统病毒中和试验，用于检测针对 RBD 的总中和抗体。此外，结果显示海藻酸钠具有安全性，支持将其用作替代天然佐剂。
