Improved molecular diagnosis of COVID-19 by the novel, highly sensitive and specific COVID-19-RdRp/Hel real-time reverse transcription-PCR assay validated in vitro and with clinical specimens

Jasper Fuk Woo Chan, Cyril Chik Yan Yip, Kelvin Kai Wang To, Tommy Hing Cheung Tang, Sally Cheuk Ying Wong, Kit Hang Leung, Agnes Yim Fong Fung, Anthony Chin Ki Ng, Zijiao Zou, Hoi Wah Tsoi, Garnet Kwan Yue Choi, Anthony Raymond Tam, Vincent Chi Chung Cheng, Kwok Hung Chan, Owen Tak Yin Tsan, Kwok Yung Yuen

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767 Citations (Scopus)

Abstract

On 31 December 2019, the World Health Organization was informed of a cluster of cases of pneumonia of unknown etiology in Wuhan, China. Subsequent investigations identified a novel coronavirus, now named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), from the affected patients. Highly sensitive and specific laboratory diagnostics are important for controlling the rapidly evolving SARS-CoV-2-associated coronavirus disease 2019 (COVID-19) epidemic. In this study, we developed and compared the performance of three novel real-time reverse transcription-PCR (RT-PCR) assays targeting the RNA-dependent RNA polymerase (RdRp)/helicase (Hel), spike (S), and nucleocapsid (N) genes of SARS-CoV-2 with that of the reported RdRp-P2 assay, which is used in >30 European laboratories. Among the three novel assays, the COVID-19-RdRp/Hel assay had the lowest limit of detection in vitro (1.8 50% tissue culture infective doses [TCID50]/ml with genomic RNA and 11.2 RNA copies/reaction with in vitro RNA transcripts). Among 273 specimens from 15 patients with laboratory-confirmed COVID-19 in Hong Kong, 77 (28.2%) were positive by both the COVID-19-RdRp/Hel and RdRp-P2 assays. The COVID-19-RdRp/Hel assay was positive for an additional 42 RdRp-P2-negative specimens (119/ 273 [43.6%] versus 77/273 [28.2%]; P < 0.001), including 29/120 (24.2%) respiratory tract specimens and 13/153 (8.5%) non-respiratory tract specimens. The mean viral load of these specimens was 3.21×104 RNA copies/ml (range, 2.21×102 to 4.71×105 RNA copies/ml). The COVID-19-RdRp/Hel assay did not cross-react with other human-pathogenic coronaviruses and respiratory pathogens in cell culture and clinical specimens, whereas the RdRp-P2 assay cross-reacted with SARS-CoV in cell culture. The highly sensitive and specific COVID-19-RdRp/Hel assay may help to improve the laboratory diagnosis of COVID-19.

Original languageEnglish
Article numbere00310-20
JournalJournal of Clinical Microbiology
Volume58
Issue number5
DOIs
Publication statusPublished - May 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
Copyright © 2020 Chan et al.

ASJC Scopus Subject Areas

  • Microbiology (medical)

Keywords

  • Coronavirus
  • COVID-19
  • Diagnostic
  • Emerging
  • PCR
  • SARS
  • Virus
  • Wuhan

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