Optimization of reaction condition of recombinase polymerase amplification to detect SARS-CoV-2 DNA and RNA using a statistical method

Juma, Kevin Maafu; Takita, Teisuke; Ito, Kenji; Yamagata, Masaya; Akagi, Shihomi; Arikawa, Emi; Kojima, Kenji; Biyani, Manish; Fujiwara, Shinsuke; Nakura, Yukiko; Yanagihara, Itaru; Yasukawa, Kiyoshi

Recombinase polymerase amplification (RPA) is an isothermal reaction that amplifies a target DNA sequence with a recombinase, a single-stranded DNA-binding protein (SSB), and a strand-displacing DNA polymerase. In this study, we optimized the reaction conditions of RPA to detect SARS-CoV-2 DNA and RNA using a statistical method to enhance the sensitivity. In vitro synthesized SARS-CoV-2 DNA and RNA were used as targets. After evaluating the concentration of each component, the uvsY, gp32, and ATP concentrations appeared to be rate-determining factors. In particular, the balance between the binding and dissociation of uvsX and DNA primer was precisely adjusted. Under the optimized condition, 60 copies of the target DNA were specifically detected. Detection of 60 copies of RNA was also achieved. Our results prove the fabrication flexibility of RPA reagents, leading to an expansion of the use of RPA in various fields.