Rajil Navid, Esmaeili Shahriar, Neuman Benjamin W, Nessler Reed, Wu Hung-Jen, Yi Zhenhuan, Brick Robert W, Sokolov Alexei V, Hemmer Philip R, Scully Marlan O
Institute for Quantum Science and Engineering, Texas A&M university, TX 77843, US.
Department of Biology, Texas A&M University, College Station, TX 77843, US.
ArXiv. 2021 Oct 13:arXiv:2110.06755v1.
In a viral pandemic, a few important tests are required for successful containment of the virus and reduction in severity of the infection. Among those tests, a test for the neutralizing ability of an antibody is crucial for assessment of population immunity gained through vaccination, and to test therapeutic value of antibodies made to counter the infections. Here, we report a sensitive technique to detect the relative neutralizing strength of various antibodies against the SARS-CoV-2 virus. We used bright, photostable, background-free, fluorescent upconversion nanoparticles conjugated with SARS-CoV-2 receptor binding domain as a phantom virion. A glass bottom plate coated with angiotensin-converting enzyme 2 (ACE-2) protein imitates the target cells. When no neutralizing IgG antibody was present in the sample, the particles would bind to the ACE-2 with high affinity. In contrast, a neutralizing antibody can prevent particle attachment to the ACE-2-coated substrate. A prototype system consisting of a custom-made confocal microscope was used to quantify particle attachment to the substrate. The sensitivity of this assay can reach 4.0 ng/ml and the dynamic range is from 1.0 ng/ml to 3.2 {\mu}g/ml. This is to be compared to 19 ng/ml sensitivity of commercially available kits.
在病毒性大流行期间，为成功控制病毒并降低感染的严重程度，需要进行一些重要检测。在这些检测中，抗体中和能力检测对于评估通过疫苗接种获得的群体免疫力以及检测用于对抗感染的抗体的治疗价值至关重要。在此，我们报告一种灵敏的技术，用于检测各种抗体针对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）病毒的相对中和强度。我们使用与SARS-CoV-2受体结合域偶联的明亮、光稳定、无背景的荧光上转换纳米颗粒作为模拟病毒粒子。涂有血管紧张素转换酶2（ACE-2）蛋白的玻璃底板模拟靶细胞。当样品中不存在中和性IgG抗体时，颗粒将以高亲和力结合到ACE-2上。相反，中和抗体可阻止颗粒附着到涂有ACE-2的底物上。使用由定制共聚焦显微镜组成的原型系统来量化颗粒与底物的附着情况。该检测方法的灵敏度可达4.0 ng/ml，动态范围为1.0 ng/ml至3.2 μg/ml。相比之下，市售试剂盒的灵敏度为19 ng/ml。
