Egelkrout Erin, Maj Magdalena, Manjarin Rodrigo, Fake Gina, Watanabe Muneaki, Williams Jenna, Blanchard Nate, Walker John, Hayden Celine, Howard John
Applied Biotechnology Institute, California Polytechnic Tech Park, San Luis Obispo, CA 93407, USA.
Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
Viruses. 2024 Dec 24;17(1):7. doi: 10.3390/v17010007.
Coronaviruses continue to disrupt health and economic productivity worldwide. Porcine epidemic diarrhea virus (PEDV) is a devastating swine disease and SARS-CoV-2 is the latest coronavirus to infect the human population. Both viruses display a similar spike protein on the surface that is a target of vaccine development. Despite the availability of commercial vaccines for both viruses, there is still a high occurrence of infections and a great need for enhanced efficacy and lower costs. We previously produced the PEDV spike protein (S) using transgenic maize, enabling a low-cost supply of the vaccine candidate. In this study, we (1) test orally delivered PEDV vaccine candidates in pigs to optimize the mucosal immune response; (2) generate the SARS-CoV-2 S1 protein in maize; and (3) perform structural characterization of the S1 protein for PEDV and SARS-CoV-2. We demonstrated high expression levels in maize of the S1 subunit of the SARS-CoV-2 spike protein, both with and without fusion to the heat-labile enterotoxin B (LTB) subunit. We found that the LTB fusion protein from both coronaviruses preferentially assembles into higher molecular weight multimers, consistent with the formation of trimers. For PEDV, administering the spike protein fused to LTB to young pigs elicited a higher level of mucosal IgAs compared to maize grain containing the S1 protein alone or controls. This suggests that fusing the coronavirus spike protein with LTB may provide better protection.
冠状病毒持续在全球范围内扰乱健康和经济生产力。猪流行性腹泻病毒（PEDV）是一种极具破坏力的猪病，而严重急性呼吸综合征冠状病毒2（SARS-CoV-2）是最新感染人类的冠状病毒。两种病毒在表面都展示出一种相似的刺突蛋白，该蛋白是疫苗研发的靶点。尽管这两种病毒都有商用疫苗，但感染率仍然很高，迫切需要提高疫苗效力并降低成本。我们之前利用转基因玉米生产了PEDV刺突蛋白（S），从而能够低成本供应候选疫苗。在本研究中，我们（1）在猪身上测试口服递送的PEDV候选疫苗，以优化黏膜免疫反应；（2）在玉米中生成SARS-CoV-2 S1蛋白；（3）对PEDV和SARS-CoV-2的S1蛋白进行结构表征。我们证明了SARS-CoV-2刺突蛋白S1亚基在玉米中的高表达水平，无论是否与不耐热肠毒素B（LTB）亚基融合。我们发现，两种冠状病毒的LTB融合蛋白优先组装成更高分子量的多聚体，这与三聚体的形成一致。对于PEDV，与单独含有S1蛋白的玉米粒或对照相比，给幼猪施用与LTB融合的刺突蛋白可引发更高水平的黏膜IgA。这表明将冠状病毒刺突蛋白与LTB融合可能提供更好的保护。
