Abstract

The 2019 novel coronavirus disease (COVID-19) is the disease that has been identified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but the prophylactic treatment of SARS-CoV-2 is still under investigation. The effective delivery of eukaryotic expression plasmids to the immune system’s inductive cells constitutes an essential requirement for generating effective DNA vaccines. Here, we have explored the use of Salmonella typhimurium as vehicles to deliver expression plasmids orally. The attenuated Salmonella phoP was constructed by the one-step gene inactivation method, and plasmid-encoded the spike protein of SARS-CoV-2 was transform into the Salmonella phoP by electroporation. Western blot experiment was used for the detection of SARS-CoV-2 expression on 293T cells. Wistar rats were immunized orally with Salmonella that carried a eukaryotic expression plasmid once a week for three consecutive weeks. The ELISA was performed to measure the SARS-CoV-2 specific IgG at rat’s serum samples. pSARS-CoV-2 can be successfully expression on 293T cells, and all immunized animals generated immunity against the SARS-CoV-2 spike protein, indicating that a Salmonella-based vaccine carrying the Spike gene can elicit SARS-CoV-2-specific secondary immune responses in rats. Oral delivery of SARS-CoV-2 DNA vaccines using attenuated Salmonella typhimurium may help develop a protective vaccine against SARS-CoV-2 infection.

中文翻译：

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使用减毒鼠伤寒沙门氏菌作为载体在大鼠体内口服 SARS-CoV-2 DNA 疫苗

摘要

2019新型冠状病毒病（COVID-19）是已被确定为严重急性呼吸系统综合症冠状病毒2（SARS-CoV-2）的疾病，但SARS-CoV-2的预防性治疗仍在研究中。将真核表达质粒有效递送至免疫系统的诱导细胞是产生有效 DNA 疫苗的基本要求。在这里，我们探索了使用鼠伤寒沙门氏菌作为载体来口服表达质粒。通过一步基因灭活法构建减毒沙门氏菌phoP ，将SARS-CoV-2的刺突蛋白质粒编码转化为沙门氏菌phoP通过电穿孔。Western blot实验用于检测SARS-CoV-2在293T细胞上的表达。连续三周每周一次用携带真核表达质粒的沙门氏菌对Wistar 大鼠进行口服免疫。进行 ELISA 以测量大鼠血清样本中的 SARS-CoV-2 特异性 IgG。pSARS-CoV-2 可以在 293T 细胞上成功表达，所有免疫动物都产生了针对 SARS-CoV-2 刺突蛋白的免疫力，这表明携带刺突基因的沙门氏菌疫苗可以引发 SARS-CoV-2 特异性二次免疫大鼠的免疫反应。使用减毒鼠伤寒沙门氏菌口服 SARS-CoV-2 DNA 疫苗可能有助于开发针对 SARS-CoV-2 感染的保护性疫苗。