Figure 6.

Principle of nucleic acid sequence-based amplification. This figure was drawn using biorender software online (https://app.biorender.com/). Nucleic acid sequence-based amplification uses three enzymes (RNaseH, AMV-RT and T7 RNA polymerase) and two primers (primer P1 and primer P2). After RNA extraction of the sample, it enters the cyclic amplification process through primers (primer P1 and primer P2) and two successive reverse transcriptase reactions and the product was directly single-stranded anti-sense RNA (anti-sense RNA).