Development and application of a recombinase-aided amplification combined with a lateral flow dipstick assay for rapid visual detection of anguillid herpesvirus 1.

Eel (Anguilla sp.) is an important freshwater-cultured species with high economic value in China. Anguillid herpesvirus 1 (AngHV-1) has been proven to be the pathogen of "mucus sloughing and haemorrhagic septicaemia disease" in eels, resulting in significant mortality and substantial losses to the eel industry. Current diagnostic methods for detecting AngHV-1 are limited to laboratory-based tests, for example, conventional end-point PCR and qPCR. Therefore, there is an urgent need to develop an accurate, rapid, and simple detection method for on-site diagnosis of AngHV-1. In this study, we developed a recombinase-aided amplification combined lateral flow dipstick (RAA-LFD) assay for the detection of AngHV-1. The RAA-LFD assay can be performed within a temperature range of 18-45°C, with a reaction time of just 10 min for amplification. Importantly, the established RAA-LFD assay exhibited no reactivity with other common aquatic viral pathogens, indicating its high specificity. The limit of detection for this method is 10 copies of AngHV-1, which is more sensitive than the established conventional end-point PCR method similarly targeting ORF95. Clinical detection of the diseased samples demonstrated that the accuracy of RAA-LFD was significantly higher than that of the conventional end-point PCR. In conclusion, the developed RAA-LFD assay has proven to be a convenient, rapid, sensitive, and reliable tool for on-site diagnosis of AngHV-1. This advancement will be invaluable for the prevention and control of AngHV-1 in the eel farming industry.