MaxCyte®: A Versatile Tool for SARS-CoV-2 Response
COVID-19 caused by SARS-CoV-2 has proven to be an incredible burden on global health care systems. New viral variants continue to emerge and spread worldwide, emphasizing the need for rapid, meaningful research to guide an effective pandemic response. Simultaneous development of fast, quantitative diagnostics to trace disease spread and prevalence combined with the generation of new vaccines promote a comprehensive approach to combating the virus. MaxCyte electroporation is a versatile technology for both highly efficient protein production and cellular engineering. Here, we present data illustrating how MaxCyte enabled not only novel vaccine development but also new diagnostic techniques and cell-based high throughput drug candidate screening. MaxCyte is an essential biotechnology platform empowering fundamental SARS-CoV-2 research.
MaxCyte enabled vaccine development
The AdCOVID vaccine candidate developed here is a replication-deficient adenovirus type 5 vector that expresses the human gene for the receptor-binding domain (RBD) for the SARS-CoV-2 spike1 . Recombinant plasmids encoding viral genes were electroporated into PER.C6 cells using the MaxCyte STxTM instrument. Newly synthesized virus was purified from cell lysates. The safety and efficacy of the AdCOVID vaccine were determined through single intranasal dose administered in mice.
Rapid and Sensitive Detection of SARS-CoV-2 Antibodies by Biolayer Interferometry
Biolayer interferometry immunosorbent assay (BLI-ISA) is a new diagnostic for the detection of SARS-CoV-2 antibodies.2 This new assay uses a simple automated process that takes less than 20 minutes and delivers real-time measurements of total antibody levels and specific antibody isotypes. CHO-S cells were transfected with an expression plasmid for RBD using MaxCyte Flow Electroporation®. The antigen was then harvested and purified from the cells. Biosensors were dipped into RBD antigens and used to test plasma for antibodies against SARS-CoV-2. As antibodies bind to antigens, real-time measurements within the sensor record the change in the reflected wavelength of light over time, resulting in a semi-quantitative measurement of the antibodies present in patient plasma.
A Cell-Based High Throughput Screening Assay for SARS-CoV-2 Drug Candidates
MaxCyte electroporation (EP) enabled the development of a genetically engineered reporter cell line essential for a new cell-based high throughput screening platform. Electroporation allowed for the simultaneous delivery of an engineered firefly luciferase (Fluc) reporter plasmid and a plasmid expressing the SARS-CoV-2 papain-like protease (PLpro) into HEK293 cells. The Fluc reporter plasmid was engineered to express a target peptide sequence containing a PLpro cleavage site. Inhibitors of PLpro prevent the enzyme from cleaving its target sequence, hindering Fluc dimerization decreasing luminescence compared to untreated cells. Identified targets were further validated by additional enzymatic and cell-based assays3
HTS Campaign Statistics
|Library||Stage||Concentration||# Samples||# Replicates||# Plates||Z’||S:B||Hit Cutoff||# Hits|
|ReFRAME||Primary||10 µM||13,104||1||11||0.71 ± 0.04||11.38 ± 1.57||35.1%||212|
|Titration||20 µM||210||3||6||0.72 ± 0.03||18.39 ± 1.30||IC50 < 10 µM||164|
|Titration CS||20 µM||210||3||6||0.76 ± 0.02||3.02 ± 0.15||IC50 < 10 µM||185|
- MaxCyte enabled the modeling of an effective prophylactic AdCOVID vaccine for SARS-CoV-2.
- MaxCyte Flow Electroporation produced high quality antigens for a new rapid semi-quantitative diagnostic assay that can aid the study of SARS-CoV-2 prevalence.
- MaxCyte scalability enabled the development of a cell-based high throughput screening platform to identify potential drug candidates for COVID-19 treatment.
- MaxCyte electroporation is a versatile technology empowering fundamental SARS-CoV-2 research.
- King RG, Silva-Sanchez A, Peel JN, et al. Single-Dose Intranasal Administration of AdCOVID Elicits Systemic and Mucosal Immunity against SARS-CoV-2 and Fully Protects Mice from Lethal Challenge. Vaccines (Basel). 2021;9(8):881. Published 2021 Aug 9. doi:10.3390/vaccines9080881
- Dzimianski JV, Lorig-Roach N, O’Rourke SM, Alexander DL, Kimmey JM, DuBois RM. Rapid and sensitive detection of SARS-CoV-2 antibodies by biolayer interferometry. Sci Rep. 2020;10(1):21738. Published 2020 Dec 10. doi:10.1038/s41598-020-78895-x
- Smith E, Davis-Gardner ME, Garcia-Ordonez RD, et al. High-Throughput Screening for Drugs That Inhibit Papain-Like Protease in SARS-CoV-2. SLAS Discov. 2020;25(10):1152-1161. doi:10.1177/2472555220963667
Corresponding Author: James Brady; [email protected] MaxCyte, Inc., Tel: (301) 944-1700