SARS-CoV-2重组S1和S蛋白疫苗诱导保护性免疫的研究

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

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0.1μg/只、1μg/只、5μg/只、10μg/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。

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 0.1μg,1μg,5μg and 10μg 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.1.621,501 Y.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.