Inhibition of grass carp reovirus with PEGylated aptamers

Grass carp reovirus (GCRV) causes a hemorrhagic disease in fingerlings and yearlings of grass carps and there is no effective preventive measure. Aptamers have the potential to inhibit viral infections. In this study, aptamers against GCRV were selected and modified with polyethylene glycol (PEG). First, the aptamers were reacted with PEG for different reaction times and at various ratios of aptamers to PEG to determine the optimal PEGylation conditions: aptamer to PEG molar ratio was 1:30 with 4 h. Then, various molecular weights PEG preparations were tested for modifying the aptamers. Cell cytotoxicity tests of the PEGylated indicated that the modified aptamers did not affect cell viability. In vitro virus inhibition assays, PEGylated aptamers with a concentration of 300 nM showed that they could reduced the virus titers at least 10 times either when the aptamers were added at the same time of GCRV infection or when they were pre-incubated with the host cells for 24 h before being infected with GCRV. However, unmodified aptamers reduced virus titers only when the aptamers were added at the samed time of GCRV infection. The results suggested that the PEGylated aptamers were more stable and could be used as therapeutic molecules against GCRV infection.