A homogeneous split-luciferase assay for rapid and sensitive detection of anti-SARS CoV-2 antibodies

Yao, Zhong; Drecun, Luka; Aboualizadeh, Farzaneh; Kim, Sun Jin; Li, Zhijie; Wood, Heidi; Valcourt, Emelissa J.; Manguiat, Kathy; Plenderleith, Simon; Yip, Lily; Li, Xinliu; Zhong, Zoe; Yue, Feng Yun; Closas, Tatiana; Snider, Jamie; Tomic, Jelena; Drews, Steven J.; Drebot, Michael A.; McGeer, Allison; Ostrowski, Mario; Mubareka, Samira; Rini, James M.; Owen, Shawn; Stagljar, Igor

Better diagnostic tools are needed to combat the ongoing COVID-19 pandemic. Here, to meet this urgent demand, we report a homogeneous immunoassay to detect IgG antibodies against SARS-CoV-2. This serological assay, called SATiN, is based on a tri-part Nanoluciferase (tNLuc) approach, in which the spike protein of SARS-CoV-2 and protein G, fused respectively to two different tNLuc tags, are used as antibody probes. Target engagement of the probes allows reconstitution of a functional luciferase in the presence of the third tNLuc component. The assay is performed directly in the liquid phase of patient sera and enables rapid, quantitative and low-cost detection. We show that SATiN has a similar sensitivity to ELISA, and its readouts are consistent with various neutralizing antibody assays. This proof-of-principle study suggests potential applications in diagnostics, as well as disease and vaccination management.