Development and evaluation of real-time fluorescence recombinase aided amplification assay without extracting nucleic acid for detection of adenovirus type 3

Objective To establish a real-time fluorescence recombinase acid amplification (RAA) method for the detection of adenovirus type 3(HAdV-3)without extraction nucleic acid. Methods According to the conserved sequence of adenovirus type 3 gene, a pair of primers and a probe were designed, and a real-time fluorescence RAA without extracting nucleic acid was established and optimizing the condition of DNA-free extraction. The sensitivity of the method was analyzed by a series of dilution and the specificity of the method was evaluated by detecting the original samples of other respiratory viruses. The clinical samples of HAdV-3 were detected and compared with the traditional real-time fluorescence quantitative PCR method for nucleic acid extraction. Results The sensitivity of the real-time fluorescence RAA method was as high as that of qPCR in the detection of 10 series diluted HAdV-3 strains. The highest corresponding CT value of qPCR was 36.87. The sensitivity of the real-time fluorescence RAA method was similar to that of the real-time fluorescence quantitative PCR method . There was no cross-reaction to other common types of respiratory viruses. The two method were used to detect 56 clinical samples at the same time, and the result were completely consistent. Conclusions We provide the first report of the real-time fluorescent RAA assays for the detection of HAdV-3 without extracting nucleic acid and it has high sensitivity and specificity. Is suitable for rapid detection of HAdV-3 in clinical laboratories and on-site unite. Key words: Human adenovirus-3; Non-extracting; Recombinase acid amplification; Detection