Browsing by Author "Ahmed Abd El Wahed"

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    A Field-Deployable Reverse Transcription Recombinase Polymerase Amplification Assay for Rapid Detection of the Chikungunya Virus
    (2016-09-29) Pranav Patel; Ahmed Abd El Wahed; Oumar Faye; Pauline Prüger; Marco Kaiser; Sasikanya Thaloengsok; Sukathida Ubol; Anavaj Sakuntabhai; Isabelle Leparc-Goffart; Frank T. Hufert; Amadou A. Sall; Manfred Weidmann; Matthias Niedrig; Robert Koch Institut; Universität Göttingen; Institut Pasteur de Dakar; GenExpress GmbH; Mahidol University; Institut Pasteur, Paris; Institute for Biomedical Research of the French Armed Forces (IRBA); Brandenburg Medical School; University of Stirling
    © 2016 Patel et al. Background: Chikungunya virus (CHIKV) is a mosquito-borne virus currently transmitted in about 60 countries. CHIKV causes acute flu-like symptoms and in many cases prolonged musculoskeletal and joint pain. Detection of the infection is mostly done using RT-RCR or ELISA, which are not suitable for point-of-care diagnosis. Methodology/Principal Findings: In this study, a reverse transcription recombinase polymerase amplification (RT-RPA) assay for the detection of the CHIKV was developed. The assay sensitivity, specificity, and cross-reactivity were tested. CHIKV RT-RPA assay detected down to 80 genome copies/reaction in a maximum of 15 minutes. It successfully identified 18 isolates representing the three CHIKV genotypes. No cross-reactivity was detected to other alphaviruses and arboviruses except O'nyong'nyong virus, which could be differentiated by a modified RPA primer pair. Seventy-eight samples were screened both by RT-RPA and real-time RT-PCR. The diagnostic sensitivity and specificity of the CHIKV RT-RPA assay were determined at 100%. Conclusions/Significance: The developed RT-RPA assay represents a promising method for the molecular detection of CHIKV at point of need.
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    Recombinase polymerase amplification assay for rapid diagnostics of dengue infection
    (2015-06-15) Ahmed Abd El Wahed; Pranav Patel; Oumar Faye; Sasikanya Thaloengsok; Doris Heidenreich; Ponpan Matangkasombut; Khajohnpong Manopwisedjaroen; Anavaj Sakuntabhai; Amadou A. Sall; Frank T. Hufert; Manfred Weidmann; Deutsches Primatenzentrum; Mansoura University; Robert Koch Institut; Institut Pasteur de Dakar; Mahidol University; Universitatsmedizin Gottingen; Institut Pasteur, Paris; Brandenburg Medical School Theodor Fontane; University of Stirling
    © 2015 Abd El Wahed et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Background: Over 2.5 billion people are exposed to the risk of contracting dengue fever (DF). Early diagnosis of DF helps to diminish its burden on public health. Real-time reverse transcription polymerase amplification assays (RT-PCR) are the standard method for molecular detection of the dengue virus (DENV). Real-time RT-PCR analysis is not suitable for on-site screening since mobile devices are large, expensive, and complex. In this study, two RT-recombinase polymerase amplification (RT-RPA) assays were developed to detect DENV1-4. Methodology/Principal Findings: Using two quantitative RNA molecular standards, the analytical sensitivity of a RT-RPA targeting the 3′non-translated region of DENV1-4 was found to range from 14 (DENV4) to 241 (DENV1-3) RNA molecules detected. The assay was specific and did not cross detect other Flaviviruses. The RT-RPA assay was tested in a mobile laboratory combining magnetic-bead based total nucleic acid extraction and a portable detection device in Kedougou (Senegal) and in Bangkok (Thailand). In Kedougou, the RT-RPA was operated at an ambient temperature of 38°C with auxiliary electricity tapped from a motor vehicle and yielded a clinical sensitivity and specificity of 98% (n=31) and 100% (n=23), respectively. While in the field trial in Bangkok, the clinical sensitivity and specificity were 72% (n=90) and 100% (n=41), respectively. Conclusions/Significance: During the first 5 days of infection, the developed DENV1-4 RT-RPA assays constitute a suitable accurate and rapid assay for DENV diagnosis. Moreover, the use of a portable fluorescence-reading device broadens its application potential to the point-of-care for outbreak investigations.