Development of Inactivated SARS-CoV-2 Control for Antigen-Based Assays
Background
Rapid antigen tests for SARS-CoV-2 were an important tool during the COVID-19 pandemic because of their significant cost advantage and ease of use. Effective and efficient development and validation of these tests require high-quality control materials that have proven performance on this test method. The objective of this study was to develop an inactivated SARS-CoV-2 control for use on antigen-based assays.
Methodology
We developed an irradiation-based inactivation protocol that sought to provide complete inactivation of the virus and improved retention of viral protein over heat inactivation. Infectivity assay was used to confirm the absence of infectious virus, while ELISA was used to quantify nucleocapsid protein (N protein) in inactivated SARS-CoV-2 samples. PROtrol™ SARS-COV-2 samples were further evaluated for reactivity on four commercially available lateral flow immunoassay tests (LFIA).
Results
The infectivity assay showed that inactivated samples did not exhibit any cytopathic effects (CPE), thus indicating the absence of infectious virus. The N protein was measured in infectious (CF), irradiated (PROtrol), and heat-inactivated (CFHI) culture fluids. The results demonstrate that when compared to infectious CFs, PROtrol products show superior retention of SARS- CoV-2 N protein immunoreactivity than CFHIs. Retention of the N protein reactivity was further demonstrated through consistent and predictable reactivity on 4 commercially available SARS-COV-2 LFIAs.
Conclusion
This study demonstrates that we have successfully developed PROtrol SARS-CoV-2, an inactivated control for antigen-based assays. Irradiation effectively inactivated the virus while preserving protein structure better than heat inactivation. The infectivity assay confirmed the absence of infectious virus, and ELISA detected nucleocapsid protein in the inactivated samples.
Products Used in This Study
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