CRISPR anti-tag-mediated room-temperature RNA detection using CRISPR/Cas13a.

The CRISPR/Cas13a enzyme serves as a powerful tool for RNA detection due to its RNA-targeting capabilities. However, simple and highly sensitive detection using Cas13a faces challenges, such as the need for pre-amplification and elevated reaction temperatures. In this study, we investigate the allosteric regulation mechanism of Cas13a activation by target RNAs with various structures containing the CRISPR anti-tag sequence. We discover that the target RNA secondary structure and anti-tag sequences inhibit the trans-cleavage reaction of Cas13a. By designing and introducing a specific CRISPR anti-tag hairpin, we develop CRISPR Anti-tag Mediated Room-temperature RNA Detection (CARRD) using a single CRISPR/Cas13a enzyme. This method enables one-step cascade signal amplification for RNA detection without the need for pre-amplification. We apply the CARRD method to detect human immunodeficiency virus (HIV) and hepatitis C virus (HCV), achieving a detection sensitivity of 10 aM. Furthermore, we validate its clinical feasibility by detecting HIV clinical plasma samples, demonstrating a simple, affordable, and efficient approach for viral RNA detection. Due to its simplicity, sensitivity, and flexible reaction temperature, the CARRD method is expected to have broad applicability, paving the way for the development of field-deployable diagnostic tools.