Aptamer-mediated targeted siRNA delivery against grouper iridovirus infection

Abstract Grouper iridovirus causes devastating infections of cultured groupers worldwide, which results in great economic losses. However, there is currently no approved antiviral treatment to counter iridovirus disease. Aptamers are molecular ligands with high specificity for targets. Aptamer LYGV1 was generated against grouper iridovirus (SGIV)-infected cells using SELEX technology, with a high binding affinity of 32.55 nM. LYGV1 specially bound to SGIV-infected cells with no cytotoxicity. In this study, cellular internalization of structurally optimized aptamer LYBV1c was explored. The results confirmed that aptamer LYGV1c was specifically and efficiently internalized into SGIV-infected cells, indicating that LYGV1c is a promising vehicle for targeted delivery of therapeutic molecules to diseased cells. Aptamer LYGV1c was coupled to small interfering RNAs (LYGV1c-siRNAs) through streptavidin bridges. The resulting LYGV1c-siRNA conjugates specially bound to SGIV-infected cells, but not normal cells, and then were actively endocytosed. The targeted cellular delivery of LYGV1c-siRNAs markedly inhibited SGIV infection both in vitro and in vivo, even more efficiently than the conventional lipid-based transfection. These results suggest that aptamers are novel and efficient vehicles for the targeted delivery of therapeutic molecules against virus infection.