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.

Establishment of pyrosequencing technology to detect White Spot Syndrome Virus (WSSV) in cultured aquatic animals.

This study aimed to establish pyrosequencing methods to detect white spot syndrome virus (WSSV). One pair of polymerase chain reaction (PCR) primers, and one pyrosequencing primer, were designed for WSSV. The pyrosequencing reaction system and conditions were optimized and a pyrosequencing method for detecting WSSV was successfully established. This method was able to specifically detect WSSV in eight viruses, with high sensitivity. The minimum detectable limit for nucleic acid was 23 copies/µL. The method was verified by detecting WSSV in 1881 batches of samples collected from domestic and imported shrimps. The detection results were more sensitive than conventional PCR. This research has therefore provided a new detection method for monitoring, and controlling aquatic animal virus diseases.