External quality assessment for the molecular detection of MERS-CoV in China

Abstract

Background: In May 2015, an imported case of Middle East respiratory syndrome coronavirus (MERS-CoV) infection occurred in China, so rapid and reliable diagnosis of suspected cases was necessary.

Objectives: An external quality assessment (EQA) program for the molecular detection of MERS-CoV was organized by the National Center for Clinical Laboratories (NCCL).

Study design: MS2 virus-like particles (VLPs) encapsulating specific RNA sequences of MERS-CoV were prepared as positive specimens. The assessment panel, which comprised of three negative and seven positive samples with different concentrations of VLPs, was distributed to 56 laboratories from 16 provinces, municipalities, or autonomous regions for molecular detection.

Results: Among the received data sets, three employed an in-house-developed real-time reverse-transcription polymerase chain reaction (rRT-PCR) assay and the others applied various commercial rRT-PCR kits. Overall, the majority of laboratories (46/56, 82.1%) could achieve 100% accuracy for MERS-CoV detection, but three laboratories (5.4%) still had room for improvement. Consequently, all negative samples were identified correctly, reaching 100% specificity. The false-negative rate was 3.1%, and most of the false-negative results were obtained from samples with relatively low concentration, indicating an urgent need to improve detection in weak-positive specimens.

Conclusions: The majority of participants possessed reliable diagnostic capacity for the detection of MERS-CoV. Moreover, EQA is indispensable because it can help enhance the diagnostic capability for the surveillance of MERS-CoV infections and allow comparison of the results among different laboratories.

Keywords: External quality assessment; MERS-CoV; MS2 virus-like particles; Molecular diagnosis; Real time RT-PCR.

Fig. 1

(A) Composition of the participants. 34 (60.7%) laboratories were provincial or municipal CDC, 13 (23.2%) laboratories belonged to designated hospitals for suspected MERS-CoV infection, and 9 (16.1%) were from commercial kit manufacturers. (B) Various nucleic acid extraction kits were applied: from QIAamp (29/56, 51.8%), the Viral RNA Mini Kit and the RNeasy Mini Kit; from Roche (8/56, 14.3%), High Pure Viral RNA Kit and MagNA Pure LC Total Nucleic Acid Isolation Kit; from TIANLONG, DNA/RNA Kit for viruses (5/56, 8.9%); from ZJ, DNA/RNA Kit for viruses (3/56, 5.4%); from TIANGEN: TIANamp RNA Kit for viruses (2/56, 3.6%), and other (9/56, 16.1%) eight RNA extraction kits. (C) Methodologies used in the EQA for MERS-CoV molecular detection. Commercially available rRT-PCR kits, 53/56 (94.6%), and in-house-developed rRT-PCR assay, 3/56 (5.4%). (D) Overall performances of the participating laboratories. Of the 56 completed data sets, the performances were found to be competent in 46 (82.1%) analyses. Seven (12.5%) participants were classified as acceptable, and three (5.4%) were included in the improvable group.