Visual Detection of SARS Coronavirus by Loop-Mediated Isothermal Amplification with Calcein Dye

Objective To develop a loop-mediated isothermal amplification(LAMP)assay for rapid visual detection of SARS coronavirus.Methods A set of six specific primers specific to eight regions of SARS ORF 1b gene were designed.The reaction was performed in a single tube at 63℃ with the addition of calcein dye prior to amplification.The Loopamp Realtime Turbidimeter was used to optimize the amplification conditions.The result was determined by the change of the color of calcein.The sensitivity and specificity of the LAMP assay were evaluated.Results The detection limit of the LAMP assay was 10 copies per tube,which was higher than that of the conventional PCR assay.The specificity of the LAMP assay was high.Only the color of the calcein in the SARS-CoV tube changed from brown into yellow-green.Conclusions The LAMP assay with calcein dye has high specificity and sensitivity.It provides a useful tool for the rapid detection of SARS-CoV.