18HLT03 SEPTIMET - Metrology to enable rapid and accurate clinical measurements in acute management of sepsis
Published January 20, 2022 | Version v1
Journal article Open

RNA reference materials with defined viral RNA loads of SARS-CoV-2—A useful tool towards a better PCR assay harmonization

Authors/Creators

  • 1. INSTAND e.V., Society for Promoting Quality Assurance in Medical Laboratories, Duesseldorf, North Rhine-Westphalia, Germany
  • 2. GBD Gesellschaft fuer Biotechnologische Diagnostik mbH, Berlin, Germany
  • 3. IQVD GmbH, Institut fuer Qualitaetssicherung in der Virusdiagnostik, Berlin, Germany
  • 4. Institute of Virology, Charite´ - University Medicine Berlin; National Consultant Laboratory for Coronaviruses; German Centre for Infection Research, Berlin, Germany
  • 5. Institute for Medical Virology, University Hospital, Goethe University Frankfurt, Frankfurt, Hesse, Germany; German Centre for Infection Research, External partner site Frankfurt, Hesse, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology, Branch Translational Medicine and Pharmacology, Frankfurt, Hesse, Germany
  • 6. Institute for Medical Virology, University Hospital, Goethe University Frankfurt, Frankfurt, Hesse, Germany
  • 7. Medizinisches Infektiologiezentrum Berlin, Germany
  • 8. Robert Koch-Institute, Centre for Biological Threats and Special Pathogens, Berlin, Germany
  • 9. Robert Koch-Institute, Department for Infectious Diseases, Berlin, Germany
  • 10. National Measurement Laboratory, LGC, Teddington, Middlesex, United Kingdom; Faculty of Health & Medical Science, School of Biosciences & Medicine, University of Surrey, Guildford, United Kingdom
  • 11. National Measurement Laboratory, LGC, Teddington, Middlesex, United Kingdom
  • 12. Materials Measurement Laboratory, Biomolecular Measurement Division, NIST, National Institute of Standards and Technology, Applied Genetics Group, Gaithersburg, Massachusetts, United States of America
  • 13. Physikalisch-Technische Bundesanstalt, Berlin, Germany
  • 14. Physikalisch-Technische Bundesanstalt, Berlin, Germany,
  • 15. ACOMED statistik, Leipzig, Saxony, Germany
  • 16. INSTAND e.V., Society for Promoting Quality Assurance in Medical Laboratories, Duesseldorf, North Rhine-Westphalia, Germany; Institute of Bioanalytical Sciences, Center of Life Sciences, Anhalt University of Applied Sciences, Bernburg, Saxony-Anhalt, Germany
  • 17. INSTAND e.V., Society for Promoting Quality Assurance in Medical Laboratories, Duesseldorf, North Rhine-Westphalia, Germany; GBD Gesellschaft fuer Biotechnologische Diagnostik mbH, Berlin, Germany; IQVD GmbH, Institut fuer Qualitaetssicherung in der Virusdiagnostik, Berlin, Germany
  • 18. INSTAND e.V., Society for Promoting Quality Assurance in Medical Laboratories, Duesseldorf, North Rhine-Westphalia, Germany; IQVD GmbH, Institut fuer Qualitaetssicherung in der Virusdiagnostik, Berlin, Germany

Description

ARS-CoV-2, the cause of COVID-19, requires reliable diagnostic methods to track the circulation of this virus. Following the development of RT-qPCR methods to meet this diagnostic need in January 2020, it became clear from interlaboratory studies that the reported Ct values obtained for the different laboratories showed high variability. Despite this the Ct values were explored as a quantitative cut off to aid clinical decisions based on viral load. Consequently, there was a need to introduce standards to support estimation of SARS-CoV-2 viral load in diagnostic specimens. In a collaborative study, INSTAND established two reference materials (RMs) containing heat-inactivated SARS-CoV-2 with SARS-CoV-2 RNA loads of ~107 copies/mL (RM 1) and ~106 copies/mL (RM 2), respectively. Quantification was performed by RT-qPCR using synthetic SARS-CoV-2 RNA standards and digital PCR. Between November 2020 and February 2021, German laboratories were invited to use the two RMs to anchor their Ct values measured in routine diagnostic specimens, with the Ct values of the two RMs. A total of 305 laboratories in Germany were supplied with RM 1 and RM 2. The laboratories were requested to report their measured Ct values together with details on the PCR method they used to INSTAND. This resultant 1,109 data sets were differentiated by test system and targeted gene region. Our findings demonstrate that an indispensable prerequisite for linking Ct values to SARS-CoV-2 viral loads is that they are treated as being unique to an individual laboratory. For this reason, clinical guidance based on viral loads should not cite Ct values. The RMs described were a suitable tool to determine the specific laboratory Ct for a given viral load. Furthermore, as Ct values can also vary between runs when using the same instrument, such RMs could be used as run controls to ensure reproducibility of the quantitative measurements.

Notes

This project (18HLT03 SEPTIMET) has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme

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18HLT03 Septimet Supplementary Funding Acknowledgement PLOS ONE.pdf

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