Rapid detection of white spot syndrome virus using aggregation-induced emission aptamer technology

Aggregation-induced emission (AIE) is a photophysical phenomenon that contrasts with aggregation-induced quenching. To date, a substantial number of AIE-based chemosensors have been reported for the detection of biological targets, metals, and small organic compounds. Aptamers, emerging molecules comprising peptide and nucleic acid types, are widely used in sensor development and various biomedical applications. This study utilizes the Aggregation-Induced Emission (AIE) principle to combine a nucleic acid aptamer targeting white spot syndrome virus (WSSV) with the AIE molecule sodium tetraphenylethylene tetracarboxylate (TPE-(COOH)₄Na), thereby constructing a fluorescent biosensor for the specific detection of WSSV. Through systematic experiments including reaction system optimization, tissue sample ratio selection, and specificity and sensitivity determination, the feasibility of this sensor for clinical detection was validated. The optimal reaction system consists of an aptamer concentration of 1 μmol/L and a molar ratio of aptamer to TPE-(COOH)₄Na of 1:120. Under these conditions, when using diseased shrimp muscle tissue as the detection sample, the background fluorescence signal was significantly lower than that of visceral tissue, indicating muscle tissue as the optimal sampling site for this method. Specificity experiments demonstrated that the sensor exhibited a significant fluorescence enhancement signal (7 715 au.) for WSSV, with fluorescence intensity approximately double that of the negative control group. In contrast, common shrimp pathogens such as shrimp hemocyte iridovirus (SHIV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), and epizootic hepatopancreatic cysticercosis (EHP) induced only weak background fluorescence (below 2 500 au). Sensitivity testing demonstrated that the sensor could detect as few as 826 copies/μL of WSSV viral particles in homogenized muscle tissue from infected shrimp. In clinical sample validation using 24 shrimp specimens, the fluorescence intensity results from this method showed 100% concordance with the national standard PCR method. However, visual interpretation under 365 nm UV light yielded 2 false positives, indicating limitations in weakly positive borderline samples. This study successfully established a highly specific and sensitive WSSV fluorescent aptamer sensor. Its core advantages include eliminating nucleic acid extraction, simplifying operation, and completing the entire detection process within 20 min. This strategy marks the first application of AIE-effect aptamer sensing technology for detecting shrimp pathogens, providing a high-performance new method for rapid field screening and early diagnosis of WSSV. It also offers a technical reference for rapid fluorescent sensing detection of other aquatic pathogens.