Rapid Development and Validation of a Novel Laboratory-Derived Test for the Detection of SARS-CoV-2

To increase testing capability for SARS-CoV-2 during a rapidly evolving public health emergency, we aimed to deploy a validated laboratory-developed real-time reverse transcription polymerase chain reaction (RT-PCR) diagnostic test for SARS-CoV-2 on an accelerated timeline and using reagent supply chains that were not constrained.

A real-time RT-PCR assay that detects the structural envelope (E) gene of SARS-CoV-2 was developed and validated on the Roche cobas 6800 instrument platform with the omni Utility channel reagents, which performs automated nucleic acid extraction and purification, PCR amplification, and detection. In silico analysis was performed for both inclusivity of all SARS-CoV-2 variants and cross reactivity with other pathogenic organisms. Positive control material was used to determine the Limit of Detection (LOD) and patient samples (positive and negative) confirmed by another authorized assay were used for clinical validation. Experiments were carried out at the Christiana Care Health System's Molecular Diagnostics Laboratory (Newark, DE) between April 1 and April 4, 2020.

A real-time RT-PCR assay for SARS-Cov-2 was developed and validated in just two weeks. For all oligonucleotides, 100% homology to the available SARS-CoV-2 sequences was observed. Greater than 80% homology between one or more oligonucleotides was observed for SARS-Cov (Urbani strain) and Influenza A, however risk of cross reactivity was deemed to be low. The limit of detection (LOD) of the assay was 250 copies/mL. The assay identified 100% of positive patient samples (30/30) and 100% of negative patient samples (29/29 patient negatives and 1/1 saline). Up to 92 samples can be run on a single plate and analysis takes approximately 3.5 hours.

In this work, we demonstrate the development and validation of a single target laboratory-developed test for SARS-CoV-2 in two weeks. Key considerations for complementary supply chains enabled development on an accelerated timeline and an increase in testing capability.