Comparative Evaluation of the Diagnostic Performance of the Prototype Cepheid GeneXpert Ebola Assay

Petrus Jansen van Vuren; Antoinette Grobbelaar; Nadia Storm; Ousman Conteh; Kelfala Konneh; Abdul Kamara; Ian Sanne; Janusz T Paweska

doi:10.1128/JCM.02724-15

Comparative Evaluation of the Diagnostic Performance of the Prototype Cepheid GeneXpert Ebola Assay

J Clin Microbiol. 2016 Feb;54(2):359-67. doi: 10.1128/JCM.02724-15. Epub 2015 Dec 4.

Authors

Petrus Jansen van Vuren¹, Antoinette Grobbelaar², Nadia Storm², Ousman Conteh³, Kelfala Konneh³, Abdul Kamara³, Ian Sanne⁴, Janusz T Paweska⁵

Affiliations

¹ Centre for Emerging and Zoonotic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham, South Africa Department of Microbiology and Plant Pathology, Faculty of Natural and Agricultural Science, University of Pretoria, Pretoria, South Africa.
² Centre for Emerging and Zoonotic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham, South Africa.
³ Ministry of Health and Sanitation, Freetown, Sierra Leone.
⁴ Clinical HIV Research Unit, Wits Health Consortium, Johannesburg, South Africa Right-to-Care, Johannesburg, South Africa.
⁵ Centre for Emerging and Zoonotic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham, South Africa Department of Microbiology and Plant Pathology, Faculty of Natural and Agricultural Science, University of Pretoria, Pretoria, South Africa Faculty of Medical Sciences, University of the Witwatersrand, Johannesburg, South Africa januszp@nicd.ac.za.

Abstract

The Ebola virus disease (EVD) outbreak in West Africa has highlighted an urgent need for point-of-care (POC) assays for the diagnosis of this devastating disease in resource-limited African countries. The diagnostic performance characteristics of a prototype Cepheid GeneXpert Ebola POC used to detect Ebola virus (EBOV) in stored serum and plasma samples collected from suspected EVD cases in Sierra Leone in 2014 and 2015 was evaluated. The GeneXpert Ebola POC is a self-contained single-cartridge automated system that targets the glycoprotein (GP) and nucleoprotein (NP) genes of EBOV and yields results within 90 min. Results from 281 patient samples were compared to the results of a TaqMan real-time reverse transcription-PCR (RT-PCR) targeting the polymerase gene and performed on two real-time PCR machines. Agreement between the three platforms was 100% at cycle threshold (CT) values of ≤34.99, but discordant results were noted between CT values of 35 and 45.The diagnostic sensitivity of the three platforms was 100% in 91 patient samples that were confirmed to be infectious by virus isolation. All three molecular platforms detected viral EBOV RNA in additional samples that did not contain viable EBOV. The analytical sensitivity of the GeneXpert Ebola POC for the detection of NP was higher, and comparable to that of polymerase gene detection, than that for the detection of GP when using a titrated laboratory stock of EBOV. There was no detectable cross-reactivity with other hemorrhagic fever viruses or arboviruses. The GeneXpert Ebola POC offers an easy to operate and sensitive diagnostic tool that can be used for the rapid screening of suspected EVD cases in treatment or in holding centers during EVD outbreaks.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cell Line
Ebolavirus / classification
Ebolavirus / genetics*
Ebolavirus / isolation & purification
Genes, Viral
Hemorrhagic Fever, Ebola / diagnosis*
Hemorrhagic Fever, Ebola / virology*
Humans
Molecular Diagnostic Techniques*
Point-of-Care Testing*
Real-Time Polymerase Chain Reaction / methods
Reproducibility of Results
Sensitivity and Specificity
Sierra Leone
Viral Load

Grants and funding

The NICD was supported by Cepheid by provision of the GeneXpert Ebola POC IV system, the GeneXpert Dx software package, disposable prototype GeneXpert Ebola cartridges, and funds for covering the costs of running polymerase (L) gene TaqMan real-time RT-PCR assays.