Rapid detection of Decapod iridescent virus 1 (DIV1) by recombinase polymerase amplification.

A recombinase polymerase amplification (RPA) assay was established for the rapid detection of Decapod iridescent virus 1 using primers targeted to the virus's ATPase gene (ORF114R). Optimization experiments showed that the optimal amplification temperature of the RPA assay was 37 °C and that the reaction could be completed within only 15 min. The target band of 15 min. is bright enough. In order to shorten the operational reaction time, consequently, 15 min was the optimal amplification time for our new RPA assay for DIV1. Specificity tests showed that the RPA assay did not exhibit any cross-reactivity with other shrimp pathogens(TSV, MrNV, YHV-1, WSSV, EHP, AHPND, EHNV, RSIV, RGV and IHHNV). Sensitivity tests further showed that the detection limit of the new RPA assay was 200 copies/50 μL, indicating that this assay was more sensitive than a nested polymerase chain reaction (PCR) method. A total of 509 clinical samples were assayed using the RPA and the PCR assays; analysis showed that the RPA method could detect weak-positive samples more effectively than the PCR method. Collectively, these findings indicated that the RPA assay was fast, simple, specific, sensitive and has significant potentials for clinical and on-site testing.