[Objective] To develop a new and rapid fluorescent recombinase-aided amplification (RAA) method for the detection of Enterocytozoon hepatopenaei (EHP), one of the major pathogens restricting the development of the prawn farming industry. [Methods] Multiple pairs of RAA primers were designed based on the highly conserved 18S rRNA gene of EHP, and the primers with the highest amplification efficiency were screened by basic RAA and fluorescent RAA. The reaction system and conditions of fluorescent RAA were then optimized. The optimization results showed that the developed method achieved detection at 37 ℃ within 20 min. Finally, the sensitivity, specificity, precision, stability, and actual sample application of the developed fluorescent RAA method were evaluated. [Results] The fluorescent RAA method had high specificity and was only sensitive to EHP, and it had no response to other pathogens causing mixed infection or secondary infection. Moreover, it had high sensitivity and high precision, with the limit of detection being 5 copies/μL and the coefficient of variation less than 5% for repeat test results. The lyophilized premix of primers and probe demonstrated good stability. It can be stably transported, used, and stored for 10 d at room temperature (25 °C) and 5 d at the high temperature (37 °C) in summer, with the shelf life longer than one year at -20 ℃. Additionally, the detection results of ninety clinical samples of prawn by the developed method were consistent with those obtained by the fluorescence quantitative PCR method recommended by fishery industry standard Code of Diagnosis for Enterocytozoon hepatopenaei Disease (SC/T 7232—2020), with the result coincidence rate of 97.78% (88/90). In addition, the fluorescent RAA method showed the sensitivity of 100.00% (30/30) and the specificity of 96.67% (58/60). [Conclusion] The established fluorescent RAA method has the characteristics of rapid detection, simple operation, high sensitivity, high specificity, high precision, and good stability, providing a technical reference for the field rapid detection of EHP. It has a wide market application prospect in the accurate and rapid detection of aquatic diseases.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |