Introduction: The worldwide affected covid-19 disease has caused deaths and irreparable economic problems. The best way to deal with such a horrible disease is to use correct and fast diagnostic methods to prevent transmission and spread of the disease. One of the methods used currently for the detection of infected patients is the LAMP method, which is an isothermal nucleic acid amplification method. The high sensitivity and specificity of this method, speed, and simplicity of analyzing the results have led to an increase in interest in it.
Methods: In the present study, 34 Oro-nasopharyngeal swab samples were first analyzed using the gold standard qRT-PCR method, and then the colorimetric RT-LAMP method was used to evaluate the possibility of SARS-COV-2 virus detection using the LAMP technique. In this study, 3 pairs of primers specific to the orf8 gene were used for the LAMP reaction and the results were evaluated according to the color change of the reaction mixture. Also, in this study, a lateral flow assay combined with the
RT-LAMP method (RT-LAMP-LFA) was designed to detect the
SARS-COV-2 virus. In this test, first, the virus genome was amplified using the RT-LAMP method and with the help of the LF primer labeled with digoxigenin and the LB primer labeled with biotin, and then the amplified products were evaluated on a lateral flow strip using the
anti-digoxigenin antibody conjugated with gold nanoparticles on the conjugation pad, Goat Anti-Mouse IgG on the control line and streptavidin on the test line. In the RT-LAMP-LFA method, the heated samples were used instead of the extracted RNA.
Results: The results of the RT-LAMP method showed a sensitivity of 93.33%
(77.93-99.18% CI:95%) and a specificity of 75% (19.41-99.37% CI: 95%) compared to the qRT-PCR technique. Also, the sensitivity and specificity of the RT-LAMP-LFA method for the detection of SARS-COV-2 virus for 44 positive samples and 22 negative samples were evaluated 100% and 77.27% respectively.
Conclusion: The results of this study showed that the RT-LAMP-LFA method can provide a quick and simple test for the detection of SARS-COV-2 virus by eliminating the time-consuming step of RNA extraction.