Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, 43210.
Texas Biomedical Research Institute, San Antonio, TX, 78227.
Proc Natl Acad Sci U S A. 2022 Aug 30;119(35):e2110105119. doi: 10.1073/pnas.2110105119. Epub 2022 Aug 22.
The spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the main target for neutralizing antibodies (NAbs). The S protein trimer is anchored in the virion membrane in its prefusion (preS) but metastable form. The preS protein has been stabilized by introducing two or six proline substitutions, to generate stabilized, soluble 2P or HexaPro (6P) preS proteins. Currently, it is not known which form is the most immunogenic. Here, we generated recombinant vesicular stomatitis virus (rVSV) expressing preS-2P, preS-HexaPro, and native full-length S, and compared their immunogenicity in mice and hamsters. The rVSV-preS-HexaPro produced and secreted significantly more preS protein compared to rVSV-preS-2P. Importantly, rVSV-preS-HexaPro triggered significantly more preS-specific serum IgG antibody than rVSV-preS-2P in both mice and hamsters. Antibodies induced by preS-HexaPro neutralized the B.1.1.7, B.1.351, P.1, B.1.427, and B.1.617.2 variants approximately two to four times better than those induced by preS-2P. Furthermore, preS-HexaPro induced a more robust Th1-biased cellular immune response than preS-2P. A single dose (10 pfu) immunization with rVSV-preS-HexaPro and rVSV-preS-2P provided complete protection against challenge with mouse-adapted SARS-CoV-2 and B.1.617.2 variant, whereas rVSV-S only conferred partial protection. When the immunization dose was lowered to 10 pfu, rVSV-preS-HexaPro induced two- to sixfold higher antibody responses than rVSV-preS-2P in hamsters. In addition, rVSV-preS-HexaPro conferred 70% protection against lung infection whereas only 30% protection was observed in the rVSV-preS-2P. Collectively, our data demonstrate that both preS-2P and preS-HexaPro are highly efficacious but preS-HexaPro is more immunogenic and protective, highlighting the advantages of using preS-HexaPro in the next generation of SARS-CoV-2 vaccines.
严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）的刺突（S）蛋白是中和抗体（NAb）的主要靶标。S 蛋白三聚体以其预融合（preS）但亚稳定形式锚定在病毒包膜中。通过引入两个或六个脯氨酸取代，可以稳定可溶性 2P 或六脯氨酸（6P）前 S 蛋白，从而稳定前 S 蛋白。目前，尚不清楚哪种形式最具免疫原性。在这里，我们生成了表达 preS-2P、preS-HexaPro 和天然全长 S 的重组水疱性口炎病毒（rVSV），并比较了它们在小鼠和仓鼠中的免疫原性。与 rVSV-preS-2P 相比，rVSV-preS-HexaPro 产生和分泌的 preS 蛋白明显更多。重要的是，rVSV-preS-HexaPro 在小鼠和仓鼠中均能诱导比 rVSV-preS-2P 更高的 preS 特异性血清 IgG 抗体。由 preS-HexaPro 诱导的抗体中和 B.1.1.7、B.1.351、P.1、B.1.427 和 B.1.617.2 变体的能力比由 preS-2P 诱导的抗体高约 2 至 4 倍。此外，与 preS-2P 相比，preS-HexaPro 诱导了更强烈的 Th1 偏向的细胞免疫反应。单次剂量（10 pfu）用 rVSV-preS-HexaPro 和 rVSV-preS-2P 免疫可完全保护小鼠适应的 SARS-CoV-2 和 B.1.617.2 变体的攻击，而 rVSV-S 仅提供部分保护。当免疫剂量降低至 10 pfu 时，rVSV-preS-HexaPro 在仓鼠中诱导的抗体反应比 rVSV-preS-2P 高 2 至 6 倍。此外，rVSV-preS-HexaPro 对肺感染的保护率为 70%，而 rVSV-preS-2P 的保护率仅为 30%。总的来说，我们的数据表明 preS-2P 和 preS-HexaPro 均具有高度疗效，但 preS-HexaPro 更具免疫原性和保护性，这突出了在下一代 SARS-CoV-2 疫苗中使用 preS-HexaPro 的优势。
