Serology testing for COVID-19 is highly attractive because of the relatively short diagnosis time and the ability to test for an active immune response against the SARS-CoV-2. In many types of serology tests, the sensitivity and the specificity are directly influenced by the quality of the antigens manufactured. Protein purification of these recombinantly expressed viral antigens [e.g., spike and its receptor binding domain (RBD)] is an important step in the manufacturing process. Simple and high-capacity protein purification schemes for spike, RBD, and CR3022 mAb, recombinantly expressed in CHO and HEK293 cells, are reported in this article. The schemes consist of an affinity chromatography step and a desalting step. Purified proteins were validated in ELISA-based serological tests. Interestingly, extracellular matrix proteins [most notably heparan sulfate proteoglycan (HSPG)] were co-purified from spike-expressing CHO culture with a long cultivation time. HSPG-spike interaction could play a functional role in the pathology and the pathogenesis of SARS-CoV-2 and other coronaviruses.

中文翻译：

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纯化重组SARS-CoV-2刺突，其受体结合结构域和CR3022 mAb以进行血清学检测

由于诊断时间相对较短，并且具有测试针对SARS-CoV-2的主动免疫反应的能力，因此COVID-19的血清学测试非常有吸引力。在许多类型的血清学测试中，敏感性和特异性直接受到所生产抗原质量的影响。这些重组表达的病毒抗原[例如，刺突及其受体结合域（RBD）]的蛋白质纯化是生产过程中的重要步骤。本文报道了在CHO和HEK293细胞中重组表达的用于穗，RBD和CR3022 mAb的简单，高容量的蛋白质纯化方案。该方案包括亲和层析步骤和脱盐步骤。纯化的蛋白质在基于ELISA的血清学测试中得到验证。有趣的是 细胞外基质蛋白[最显着的是硫酸乙酰肝素蛋白聚糖（HSPG）]是从表达穗的CHO培养物中共同纯化的，培养时间较长。HSPG-钉相互作用可能在SARS-CoV-2和其他冠状病毒的病理学和发病机理中发挥功能性作用。