Evaluation of reverse-transcription loop-mediated isothermal amplification assay for screening influenza a viruses from different animal species

For efficient monitoring of infections caused by various subtypes of Influenza A Virus (IAV) in animal populations, it is necessary to provide a rapid, accurate and reliable moleculardiagnostic assay for detection of all IAV subtypes. This study aims to evaluate a previously reported Reverse-Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) assay for detection of animal IAVs from different species. The assay is capable of visually detecting 16 subtypes of Avian IAV (AIV), three subtypes of Awine IAV (SIV), two subtypes of Equine IAV (EIV), one subtype of Canine IAV (CIV) and two subtypes of human IAV but not influenza B virus. The detection limit of the assay was 10^-2, 10^-3, 10^-1 and 10^-1 tissue culture infective dose50 for each tested AIV, SIV, EIV and CIV, respectively which was 10 fold higher than that of RT-Polymerase Chain Reaction (PCR) and the same as those of Real-Time RT-PCR (RRT-PCR) andRT-LAMP Methods for IAVs. The RT-LAMP Method detected eight samples as IAV-positive out of 589 field samples which was consistent with RRT-PCR and virus isolation results. The RT-LAMP assay evaluated in this study is applicable for rapid, user-friendly and reliable screening of IAV in animal populations and is expected to be an alternative method to RT-PCR or RRT-PCR, even in under-equipped laboratories.