Signal-enhanced visual strand exchange amplification detection of African swine fever virus by the introduction of multimeric G-quadruplex/hemin DNAzyme.

African swine fever virus (ASFV) causes hemorrhagic infectious disease in pigs with a fatality rate of nearly 100%. In this study, we developed a visual strand exchange amplification detection assay for ASFV. In the presence of ASFV, DNA amplification products containing multimeric G-quadruplex sequences were amplified by strand exchange amplification. These G-quadruplexes, assembled with hemin to form DNAzyme, displayed enhanced significant "turned-on" colorimetric signals to indicate detection results. The results showed that dimeric DNAzyme had the best visualization effect. Under the optimal reaction parameters, there was a linear relationship between the absorbance of the reaction solution at 417 nm and the logarithm of ASFV concentration ranged from 1 × 10 to 1 × 10 copies/μL, and the detection limit was 2.7 copies/μL. We hoped this visual assay could be helpful in the rapid and sensitive detection of ASFV, and the results of multimeric G-quadruplex/hemin DNAzyme could be helpful for the development of better visual detection assays.