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.
