Characterization of DNA aptamers generated against the soft-shelled turtle iridovirus with antiviral effects

Abstract

Background: Soft-shelled turtle iridovirus (STIV) causes severe systemic disease in farmed soft-shelled turtles (Trionyx sinensis). More efficient methods of controlling and detecting STIV infections are urgently needed. Methods: In this study, we generated eight single-stranded DNA (ssDNA) aptamers against STIV using systematic evolution of ligands by exponential enrichment (SELEX). Results: The aptamers formed representative stem-loop secondary structures. Electrophoretic mobility shift assays and fluorescent localization showed that the selected aptamers had high binding affinity for STIV. Aptamer QA-36 had the highest calculated binding affinity (Kd) of 53.8 nM. Flow cytometry and fluorescence microscopy of cell-aptamer interactions demonstrated that QA-12 was able to recognize both STIV-infected cells and tissues with a high level of specificity. Moreover, the selected aptamers inhibited STIV infection in vitro and in vivo, with aptamer QA-36 demonstrating the greatest protective effect against STIV and inhibiting STIV infection in a dose-dependent manner. Discussion: We generated DNA aptamers that bound STIV with a high level of specificity, providing an alternative means for investigating STIV pathogenesis, drug development, and medical therapies for STIV infection. Conclusions: These DNA aptamers may thus be suitable antiviral candidates for the control of STIV infections.