Selection and characterization of ssDNA aptamer targeting Macrobrachium rosenbergii nodavirus capsid protein: A potential capture agent in gold‐nanoparticle‐based aptasensor for viral protein detection

Abstract The giant freshwater prawn holds a significant position as a valuable crustacean species cultivated in the aquaculture industry, particularly well‐known and demanded among the Southeast Asian countries. Aquaculture production of this species has been impacted by Macrobrachium rosenbergii nodavirus (MrNV) infection, which particularly affects the larvae and post‐larvae stages of the prawn. The infection has been recorded to cause mortality rates of up to 100% among the affected prawns. A simple, fast, and easy to deploy on‐site detection or diagnostic method is crucial for early detection of MrNV to control the disease outbreak. In the present study, novel single‐stranded DNA aptamers targeting the MrNV capsid protein were identified using the systematic evolution of ligands by exponential enrichment (SELEX) approach. The aptamer was then conjugated with the citrate‐capped gold nanoparticles (AuNPs), and the sensitivity of this AuNP‐based aptasensor for the detection of MrNV capsid protein was evaluated. Findings revealed that the aptamer candidate, APT‐MrNV‐CP‐1 was enriched throughout the SELEX cycle 4, 9, and 12 with the sequence percentage of 1.76%, 9.09%, and 12.42%, respectively. The conjugation of APT‐MrNV‐CP‐1 with citrate‐capped AuNPs exhibited the highest sensitivity in detecting the MrNV capsid protein, where the presence of 62.5 nM of the viral capsid protein led to a significant agglomeration of the AuNPs. This study demonstrated the practicality of an AuNP‐based aptasensor for disease diagnosis, particularly for detecting MrNV infection in giant freshwater prawns.