严重急性呼吸道综合征冠状病毒2(SARS-CoV-2),COVID-19的致病因子,编码几种辅助蛋白,这些辅助蛋白已被证明在调节先天免疫反应中起关键作用。然而,它们在受感染细胞中的表达以及在受感染的人和小鼠中的免疫原性仍未完全了解。在这项研究中,我们使用各种技术在COVID-19患者血清中检测到辅助蛋白特异性抗体,包括荧光素酶免疫沉淀系统(LIPS),免疫荧光分析(IFA),和蛋白质印迹(WB)。蛋白质3a,3b,7b,8和9c特异性抗体可通过LIPS检测,但IFA或WB仅检测到蛋白3a抗体。仅在ICU患者中检测到针对蛋白3a和7b的抗体,可以作为预测疾病进展的标志物。Further,我们研究了SARS-CoV-2感染细胞中辅助蛋白的表达,并鉴定了蛋白3a的表达,6、7a、8和9b。我们还分析了它们在免疫小鼠中诱导抗体的能力,发现只有蛋白质3a,6、7a、8、9b和9c能够诱导可测量的抗体产生,但是这些抗体缺乏中和活性,并且不能保护小鼠免受SARS-CoV-2感染。我们的发现验证了SARS-CoV-2辅助蛋白的表达,并阐明了它们的体液免疫反应。为蛋白质检测试验及其在发病机制中的作用提供依据。
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, encodes several accessory proteins that have been shown to play crucial roles in regulating the innate immune response. However, their expressions in infected cells and immunogenicity in infected humans and mice are still not fully understood. This study utilized various techniques such as luciferase immunoprecipitation system (LIPS), immunofluorescence assay (IFA), and western blot (WB) to detect accessory protein-specific antibodies in sera of COVID-19 patients. Specific antibodies to proteins 3a, 3b, 7b, 8 and 9c can be detected by LIPS, but only protein 3a antibody was detected by IFA or WB. Antibodies against proteins 3a and 7b were only detected in ICU patients, which may serve as a marker for predicting disease progression. Further, we investigated the expression of accessory proteins in SARS-CoV-2-infected cells and identified the expressions of proteins 3a, 6, 7a, 8, and 9b. We also analyzed their ability to induce antibodies in immunized mice and found that only proteins 3a, 6, 7a, 8, 9b and 9c were able to induce measurable antibody productions, but these antibodies lacked neutralizing activities and did not protect mice from SARS-CoV-2 infection. Our findings validate the expression of SARS-CoV-2 accessory proteins and elucidate their humoral immune response, providing a basis for protein detection assays and their role in pathogenesis.