Abstract 706: Rapid detection of SARS-CoV-2 antigen and antibody seroconversion in clinical specimens using a novel Surface Programmable Activation Receptor (SPAR) modified T cell diagnostic method

Abstract

Infection by SARS-CoV-2 virus or past exposure to COVID19, is of central concern to the management of cancer patient co-morbidities. Currently available testing methods require separate technologies to determine if a patient has anti- SARS-CoV-2 antibodies or if they are currently infected. A rapid, reliable, dual-use diagnostic platform deployed near the cancer patient would make a critical contribution to their care. We previously developed a biomarker detection system using modified Jurkat-T cells engineered into specific and sensitive biosensors that display a wide dynamic range with low background signal. In this system, the T cell receptor (TCR) is fused to an antibody binding domain (mouse FcγRI) and the cells are also engineered to express a high level of the calcium dependent photoprotein, aequorin. The modified TCR can be programmed for detection of a target of interest by addition of specific and appropriately tagged target detection molecules (TDMs) which bind the FcγRI.Using this system, we have developed novel assays specific for detection of SARS-CoV-2 antigen or serum antibodies against SARS-CoV-2 in clinical specimens, using mouse IgG2a-tagged TDMs provided by Twist Bioscience. For antigen detection, mouse IgG2a-Fc tagged SARS-CoV-2 spike antibody (IgG) was used as the assay TDM, sensitizing the cells to SARS-CoV-2 spike protein. For antibody detection, mouse IgG2a-Fc tagged SARS-CoV-2 spike protein (S1 domain) was used as the assay TDM with T cell activation caused by binding to serum antibodies against SARS-CoV-2 spike protein. Following binding of either target, T cell activation causes a rapid release of calcium in the modified T cells, leading to a rapid light emission by aequorin in the presence of coelenterazine, CTZ. This light emission is detectable in less than 5 minutes using a simple luminometer, and with no specimen pre-treatment. Results from both contrived and clinical specimens using each diagnostic method will be presented to demonstrate their accuracy, reproducibility, sensitivity, specificity, and speed. Results are highly reproducible at sub-nanomolar spike protein concentrations in viral transport media (VTM) and human serum, respectively. Real-world clinical seropositive specimens from convalescent COVID-19 patients as well as serum from patients exposed to related viruses or other disease states were tested using the antibody detection assay. Gamma-irradiated clinical SARS-CoV-2 isolate as well as related and unrelated viral isolates on nasal swabs were tested using the antigen detection assay. Citation Format: Aaron K. LeFebvre, Melissa Frenchmeyer, Kyle M. McQuaid, MRussell Williams, Charles M. McBrairty, Joseph D. Kittle. Rapid detection of SARS-CoV-2 antigen and antibody seroconversion in clinical specimens using a novel Surface Programmable Activation Receptor (SPAR) modified T cell diagnostic method [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 706.