Figure 3.

Schematic view of reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay. (A) Initially, the primer and reverse transcriptase (shown in purple) convert RNA to cDNA while at the same time the primer and DNA polymerase with strand displacing activity (shown in blue) make the second cDNA strand and release the first cDNA strand. The displaced single-stranded cDNA subsequently acts as a template for further extension reactions by other specific primers and DNA polymerases with strand displacing activity. The product subsequently self-anneals and forms dumbbell-shaped structures leading to subsequent rounds of exponential amplification. Reproduced and modified with permission from ref [46]. (B) The amplification process can be visually monitored by the color change of the fluorescent calcein from orange to green that indicates a positive result. Reprinted from [48] with permission from Elsevier.