Use of reverse transcriptase loop-mediated isothermal amplification assay for field detection of Newcastle disease virus using less invasive samples

Abstract

A novel nucleic acid amplification method, loop-mediated isothermal amplification, was developed and recently demonstrated detection of Newcastle disease virus (NDV) in tissue samples. But slaughter of poultry for test samples is often faced with resentment by low-income farmers. This study was undertaken to determine the test properties of reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) in detection of NDV in clinical cases using cloacal and oropharyngeal swabs. Samples included 46 tracheal tissues, 94 cloacal and 107 oro-pharyngeal swabs from on-station and 30 spleens, 74 cloacal and 74 oro-pharyngeal swabs from the field. Analysis was done using specific RT-LAMP targeting the fusion (F) protein. While the method detected NDV from swab samples, no RNA of other poultry disease viruses was amplified, indicating analytical specificity of 100%. RT-LAMP took ≤36 minutes in 83% (n=329) of positive reactions with all samples amplified in <60 minutes. Results were easily observed with a naked eye. Cloacal and oro-pharyngeal swabs could be a convenient and cheaper alternative in diagnosis of NDV infection by RT-LAMP in resource poor countries. [Vet. World 2012; 5(4.000): 206-212