The KaiBiLi COVID-19 Neutralization Ab+ Rapid Test is a lateral flow chromatographic immunoassay for the semiquantitative detection of anti-RBD IgG antibody to SARS-CoV-2 in human whole blood, serum or plasma specimen. The device can detect the concentrations of anti-RBD IgG antibody greater than or equal to 506 BAU/mL as effective antibody concentration and 5 BAU/mL as limit of detection.
Introduction
The novel coronaviruses belong to the β genus. COVID-19 is an acute respiratory infectious disease. SARS-CoV-2 has several structural proteins including spike (S), envelope (E), membrane (M) and nucleocapsid (N). The spike protein (S) contains a receptor binding domain (RBD), which is responsible for recognizing the cell surface receptor, angiotensin converting enzyme-2 (ACE2). It is found that the RBD of the SARS-CoV-2 spike protein strongly interacts with the human ACE2 receptor leading to endocytosis into the host cells of the deep lung and viral replication. Infection with the SARS-CoV-2 or vaccination initiates an immune response, which includes the production of anti-RBD IgG antibody in the blood. The secreted antibody provides protection against future infections from viruses, because it remains in the circulatory system for months to years after infection or vaccination and will bind quickly and strongly to the pathogen to block cellular infiltration and replication. Vaccine efficacy of 80% against primary symptomatic COVID-19 could be achieved with an antibody level of 506 BAU/mL for anti-RBD IgG.