Comparison of FilmArray and Quantitative Real-Time Reverse Transcriptase PCR for Detection of Zaire Ebolavirus from Contrived and Clinical Specimens

Abstract

Rapid, reliable, and easy-to-use diagnostic assays for detection of Zaire ebolavirus (ZEBOV) are urgently needed. The goal of this study was to examine the agreement among emergency use authorization (EUA) tests for the detection of ZEBOV nucleic acids, including the BioFire FilmArray BioThreat (BT) panel, the FilmArray BT-E panel, and the NP2 and VP40 quantitative real-time reverse transcriptase (qRT) PCR assays from the Centers for Disease Control and Prevention (CDC). Specimens used in this study included whole blood spiked with inactivated ZEBOV at known titers and whole-blood, plasma, and urine clinical specimens collected from persons diagnosed with Ebola virus disease (EVD). The agreement for FilmArray and qRT-PCR results using contrived whole-blood specimens was 100% (6/6 specimens) for each ZEBOV dilution from 4 ؋ 10 7 to 4 ؋ 10 2 50% tissue culture infective dose (TCID 50 )/ml, as well as the no-virus negative-control sample. The limit of detection for FilmArray and qRT-PCR assays with inactivated ZEBOV, based on duplicate positive results, was determined to be 4 ؋ 10 2 TCID 50 /ml. Rates of agreement between FilmArray and qRT-PCR results for clinical specimens from patients with EVD were 85% (23/27 specimens) for whole-blood specimens, 90% (18/20 specimens) for whole-blood specimens tested by FilmArray testing and matched plasma specimens tested by qRT-PCR testing, and 85% (11/13 specimens) for urine specimens. Among 60 specimens, eight discordant results were noted, with ZEBOV nucleic acids being detected only by FilmArray testing in four specimens and only by qRT-PCR testing in the remaining four specimens. These findings demonstrate that the rapid and easy-to-use FilmArray panels are effective tests for evaluating patients with EVD. Ebolavirus is an enveloped, single-stranded RNA virus that is the cause of Ebola virus disease (EVD). EVD is characterized by fever, emesis, diarrhea, and a hemorrhagic disorder that can include maculopapular rash, petechiae, ecchymoses, and mucosal hemorrhage (1). Zaire ebolavirus (ZEBOV) was the cause of the 2014-2015 outbreak of EVD in West Africa, which to date has resulted in 27,352 total cases, 15,052 laboratory-confirmed cases, and 11,178 deaths (2, 3).Early detection of ZEBOV is critical for the management of cases of EVD and for outbreak control. A significant challenge in areas without Ebola, such as the United States, is the rapid assessment of individuals with a history of travel to West Africa who present with symptoms of EVD. Currently, the standard protocol for EVD testing involves collection of whole blood or plasma, followed by testing using quantitative real-time reverse transcriptase (qRT) PCR assays. Although they are highly sensitive and specific, qRT-PCR assays for ZEBOV are complex, which limits their use to state public health laboratories and the Centers for Disease Control and Prevention (CDC) (4, 5). Depending on the location of the patient being tested and the laboratory performing the testing, the turnaround time for qRT-PCR results could be...

Evaluation of the Biofire FilmArray BioThreat-E Test (v2.5) for Rapid Identification of Ebola Virus Disease in Heat-Treated Blood Samples Obtained in Sierra Leone and the United Kingdom

“…Therefore, the four discrepant BioThreat-E test-positive results discussed above are consistent with the presence of residual low EBOV concentrations in blood, as was also observed in another study (7).…”

Development, Evaluation, and Integration of a Quantitative Reverse-Transcription Polymerase Chain Reaction Diagnostic Test for Ebola Virus on a Molecular Diagnostics Platform

“…The GeneXpert Ebola assay (Cepheid) and FilmArray Ebola test (BioFire) are 2 other platforms providing a fully integrated and automated PCR workflow for EVD testing, but they still require preloading manipulation steps [8,9,19,20]. In addition, we demonstrated that the Idylla™ prototype Ebola virus test can withstand a short exposure up to 40°C (2 days) and humidity of 70% at 30°C and that the cartridge reagents are stable for 4 months at 30°C, while most other PCR tests require a cold chain [18].…”

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

“…It has been shown that there is earlier clearance of virus from serum and plasma than from whole blood (27). Testing of whole blood has an important practical and safety advantage since it does not require specimen processing.…”