Selection of DNA aptamers targeting PirAB toxin for potential biosensing applications in acute hepatopancreatic necrosis disease (AHPND)

Abstract

The timely detection of AHPND is one of the key factors to avoid the great economic losses that this disease entails for aquaculture. The use of aptamers as detection tools allows us to develop a method focused on the specific needs of the producer, such as simple and easy to use, ability to carry out a safe and rapid response field detection. Vibrio parahaemolyticus is currently known as the main causal agent of AHPND in shrimp cultures, however, it is not limited to this species as a transfer of virulence factors has been observed, including the genes encoding the PirAB binary toxin. The concern that this transfer implies has led us to focus our interest on the PirAB binary toxin as a ligand for the development of aptamers capable of identifying it in the field in early stages and avoiding advanced stages of the disease, giving the producer the ability to take preventive actions and reduce the risk of losses. In the present work we have optimized the SELEX (systematic evolution of ligands by exponential enrichment) aptamer development methodology to rapidly develop candidates capable of detecting both the PirAB complex and its subunits separately, obtaining candidates with a dissociation constant (Kd) of 65 to 700 nM for the PirB subunit and 1 to 3 uM for the PirAB complex. These aptamers provide the first step toward the development of a rapid detection method targeting the causative toxin of AHPND and aid in a new user-friendly approach to early disease detection.