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

Abstract

f Rapid Ebola virus (EBOV) detection is crucial for appropriate patient management and care. The performance of the FilmArray BioThreat-E test (v2.5) using whole-blood samples was evaluated in Sierra Leone and the United Kingdom and was compared with results generated by a real-time Ebola Zaire PCR reference method. Samples were tested in diagnostic laboratories upon availability, included successive samples from individual patients, and were heat treated to facilitate EBOV inactivation prior to PCR. The BioThreat-E test had a sensitivity of 84% (confidence interval [CI], 64% to 95%) and a specificity of 89% (CI, 73% to 97%) in Sierra Leone (n ‫؍‬ 60; 44 patients) and a sensitivity of 75% (CI, 19% to 99%) and a specificity of 100% (CI, 97% to 100%) in the United Kingdom (n ‫؍‬ 108; 70 patients) compared to the reference real-time PCR. Statistical analysis (Fisher's exact test) indicated there was no significant difference between the methods at the 99% confidence level in either country. In 9 discrepant results (5 real-time PCR positives and BioThreat-E test negatives and 4 real-time PCR negatives and BioThreat-E test positives), the majority (n ‫؍‬ 8) were obtained from samples with an observed or probable low viral load. The FilmArray BioThreat-E test (v2.5) therefore provides an attractive option for laboratories (either in austere field settings or in countries with an advanced technological infrastructure) which do not routinely offer an EBOV diagnostic capability.

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

“…The diagnostic sensitivity reported by the manufacturers of the 9 Food and Drug Administration-approved EUA EBOV molecular tests varies between 87% and 100%, illustrating that the performance of the available diagnostic methods differs significantly. When evaluation was performed under field conditions in the context of the West African outbreak, the diagnostic sensitivity (84%) and specificity (87%) of the Biofire assay were shown to be lower than stated by the manufacturer [9]. Therefore, a future field evaluation of our test is required.…”

“…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].…”

“…In an epidemic context, access to accurate, rapid, highly sensitive, and easy-to-use assays with minimal manipulation of potentially highly infectious samples would therefore be a great asset [6,7]. The outbreak in West Africa spurred the development and clinical evaluation of several RT-PCR assays implemented on automated molecular detection platforms, such as the GeneXpert Ebola assay (Cepheid) [8] and the FilmArray Ebola test (BioFire) [9].…”

Diagnostic virology and patient care: from vaguely interesting to vitally important

“…[50] The Parvovirus B19 was discovered by Cossart and colleagues a few years later. They were following up the Hepatitis B work and also investigating patients' sera by EM, [51] but unexpectedly found an unrelated virus. In contrast, the HIV was isolated from human blood samples through the diligence and well-designed experiments of Montagnier and Barré-Sinousi and their team [52] who were working to find the causative agent of Acquired Immune Deficiency Syndrome (AIDS).…”

Diagnosis of Ebola Virus Disease: Past, Present, and Future

“…The largest of these studies, carried out in Public Health England laboratories in both Sierra Leone and the United Kingdom, compared the results from venipuncture whole blood tested by the FilmArray Biothreat-E test with paired plasma tested by routine clinical RT-PCR (Trombley assay) (79). The Biothreat-E test demonstrated 84% sensitivity with 89% specificity in specimens collected in Sierra Leone (n ϭ 60; 25 Ebola virus-pos-itive specimens), and 75% sensitivity with 100% specificity in specimens collected in the United Kingdom (n ϭ 108; 4 Ebola virus-positive specimens), compared to the Trombley RT-PCR.…”