Generating aptamers for specific recognition against soft-shelled turtle iridovirus infection

Soft-shelled turtle iridovirus (STIV) causes devastating virus disease in farmed soft-shelled turtles (Trionyx sinensis). Aptamers with remarkably high specificity and affinity have been widely applied in diseases diagnosis and therapies. In this study, single-stranded DNA (ssDNA) aptamers were generated against STIV-infected Fathead minnow (FHM) cells via Cell-SELEX (Cell based-Systematic Evolution of Ligands by Exponential enrichment technology). Aptamers could form stable stem-loop structures and specifically recognize STIV-infected FHM cells, with calculated dissociation constants (Kd) of 191 +/- 12 and 497 +/- 39 nM for aptamers LYST1 and LYST2, respectively, which indicated that they could serve as specific delivery system for antiviral therapies. Both aptamers displayed antiviral activities in vitro. The targets of aptamers LYST1and LYST2 in cell membranes could be membrane proteins, which were trypsin-sensitive. FAM-labeled aptamer LYST1 could identify STIV infection in diseased turtle tissues. It is the first time that aptamers against STIV-infected cells have been selected and characterized. The aptamers have great potential in development of rapid diagnostic assays and targeted antiviral drugs against STIV in aquaculture.