SARS-CoV-2重组S1和S蛋白疫苗诱导保护性免疫的研究*

目的:评价新型冠状病毒(SARS-CoV-2)重组S1蛋白和S蛋白疫苗对SARS-CoV-2的免疫保护效果。方法:将SARS-CoV-2重组S1蛋白和S蛋白分别联合氢氧化铝佐剂以0.1 μg/只、1 μg/只、5 μg/只、10 μg/只不同剂量接种6~8周BALB/c纯系健康雌性小鼠。第二次免疫后采血通过酶联免疫吸附试验(ELISA)检测血清中IgG抗体效价,通过假病毒中和试验比较免疫小鼠血清对SARS-CoV-2野生型株(WT)、英国株(B.1.1.7)、巴西株(P.1)、印度株(B.1.617.2)、Mu毒株(B.1.621)和南非株(501Y.V2-1)六种假病毒毒株中和活性效价,取脾细胞通过酶联免疫斑点技术(ELISpot)检测免疫小鼠的细胞免疫水平。结果:SARS-CoV-2重组S和S1蛋白都能诱导小鼠产生较强的IgG抗体水平。免疫S1蛋白的小鼠血清对SARS-CoV-2野生型株、英国株、巴西株有明显的中和活性,免疫S蛋白的小鼠血清除了对SARS-CoV-2野生型株、英国株、巴西株有明显中和活性之外,对印度株也有明显的中和活性,两种蛋白质免疫的小鼠血清均对野生型株中和效果最强。S蛋白免疫的小鼠脾细胞能够显著诱导出γ干扰素(IFN-γ)和白介素-4(IL-4)的产生。S蛋白诱导产生的IgG抗体、中和抗体、细胞免疫水平均高于S1。结论:SARS-CoV-2重组S蛋白疫苗能够诱导产生较强的保护性免疫应答。

Study on Protective Immunity Induced by Recombinant SARS-CoV-2 S1 and S Protein Vaccine

To evaluate the immune protection of recombinant SARS-CoV-2 S1 and S protein vaccine. Methods: Recombinant SARS-CoV-2 S1 or S protein combined with aluminum hydroxide adjuvant was inoculated at different doses of 0.1 μg, 1 μg, 5 μg and 10 μg per mouse for 6-8 weeks. Serum IgG antibody titers were detected by enzyme linked immunosorbent assay (ELISA) after second immunization. The serum neutralizing antibody titers of the immunized mice against pseudotype SARS-CoV-2-Fluc WT, B.1.1.7, P.1, B.1.617.2, B.1.621, 501Y.V2-1 strains were compared by pseudovirus neutralization test. The cellular immune levels of sera were detected by enzyme-linked immunospot assay (ELISpot).Results: Both SARS-CoV-2 S and S1 proteins could induce strong IgG antibody levels in mouse model. The sera of mice immunized with S1 protein showed obvious neutralization activity against SARS-CoV-2-Fluc WT, B.1.1.7 and P.1. The sera of mice immunized with the recombinant S protein also showed obvious neutralization activity against SARS-CoV-2-Fluc B.1.617.2 in addition to SARS-CoV-2-Fluc WT, B.1.1.7 and P.1. The serum of mice immunized with two kinds of proteins had the strongest neutralizing effect on SARS-CoV-2-Fluc WT. Mouse spleen cells immunized with S protein could significantly induce the production of interferon-γ (IFN-γ) and interleukin-4 (IL-4). The levels of IgG antibody, neutralizing antibody and cellular immunity induced by S protein were higher than those of S1.Conclusion: Recombinant SARS-CoV-2 S protein vaccine can induce protective immune responses.