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

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 (K d ) 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.