Automated SARS-COV-2 RNA extraction from patient nasopharyngeal samples using a modified DNA extraction kit for high throughput testing

Ann Saudi Med. 2020 Sep-Oct;40(5):373-381. doi: 10.5144/0256-4947.2020.373. Epub 2020 Oct 1.

Abstract

Background: The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) has prompted a need for mass testing to identify patients with viral infection. The high demand has created a global bottleneck in testing capacity, which prompted us to modify available resources to extract viral RNA and perform reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) to detect SARS-COV-2.

Objectives: Report on the use of a DNA extraction kit, after modifications, to extract viral RNA that could then be detected using an FDA-approved SARS-COV-2 RT-qPCR assay.

Materials and methods: Initially, automated RNA extraction was performed using a modified DNA kit on samples from control subjects, a bacteriophage, and an RNA virus. We then verified the automated extraction using the modified kit to detect in-lab propagated SARSCOV-2 titrations using an FDA approved commercial kit (S, N, and ORF1b genes) and an in-house primer-probe based assay (E, RdRp2 and RdRp4 genes).

Results: Automated RNA extraction on serial dilutions SARS-COV-2 achieved successful one-step RT-qPCR detection down to 60 copies using the commercial kit assay and less than 30 copies using the in-house primer-probe assay. Moreover, RT-qPCR detection was successful after automated RNA extraction using this modified protocol on 12 patient samples of SARS-COV-2 collected by nasopharyngeal swabs and stored in viral transport media.

Conclusions: We demonstrated the capacity of a modified DNA extraction kit for automated viral RNA extraction and detection using a platform that is suitable for mass testing.

Limitations: Small patient sample size.

Conflict of interest: None.

MeSH terms

  • Animals
  • Automation
  • Betacoronavirus / genetics*
  • COVID-19
  • COVID-19 Testing
  • Chlorocebus aethiops
  • Clinical Laboratory Techniques
  • Coronavirus Envelope Proteins
  • Coronavirus Infections / diagnosis*
  • Coronavirus Nucleocapsid Proteins
  • Coronavirus RNA-Dependent RNA Polymerase
  • Encephalomyocarditis virus / genetics
  • High-Throughput Nucleotide Sequencing / methods*
  • Humans
  • Levivirus / genetics
  • Nasopharynx / virology*
  • Nucleocapsid Proteins / genetics
  • Pandemics
  • Phosphoproteins
  • Pneumonia, Viral / diagnosis*
  • RNA, Viral / analysis
  • RNA, Viral / isolation & purification*
  • RNA-Dependent RNA Polymerase / genetics
  • Reverse Transcriptase Polymerase Chain Reaction / methods*
  • SARS-CoV-2
  • Sequence Analysis, RNA
  • Spike Glycoprotein, Coronavirus / genetics
  • Vero Cells
  • Viral Envelope Proteins / genetics
  • Viral Nonstructural Proteins / genetics

Substances

  • Coronavirus Envelope Proteins
  • Coronavirus Nucleocapsid Proteins
  • Nucleocapsid Proteins
  • Phosphoproteins
  • RNA, Viral
  • Spike Glycoprotein, Coronavirus
  • Viral Envelope Proteins
  • Viral Nonstructural Proteins
  • envelope protein, SARS-CoV-2
  • nucleocapsid phosphoprotein, SARS-CoV-2
  • spike protein, SARS-CoV-2
  • Coronavirus RNA-Dependent RNA Polymerase
  • NSP12 protein, SARS-CoV-2
  • RNA-Dependent RNA Polymerase

Grants and funding

This is a King Faisal Specialist Hospital & Research Centre (Saudi Arabia) funded study. The commercial Invitrogen Forensic DNA extraction kits were provided by King Abdulaziz City for Science and Technology (Saudi Arabia).