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Virus-induced central nervous system (CNS) diseases represent a significant burden to animal health worldwide. The difficulty in treating these diseases is mainly attributable to the elaborate barrier system, which limits the transport of drugs to the infected sites. Therefore, it is necessary to develop smart delivery technologies for treatment of these diseases. In the study, viral nervous necrosis disease was studied as a model to evaluate the feasibility of multiwalled carbon nanotubes (MWCNTs) conjugated with virus-specific nanobody and antiviral drug for targeted therapy of virus-induced CNS diseases. The virus (named as PGNNV) was isolated, identified and purified from diseased grouper. A nai ̈ve phage-displayed alpaca nanobody library was constructed, and the purified PGNNV was used for biopanning of PGNNVspecific nanobody from the library. The targeted delivery system based on MWCNTs conjugated with polyethylenimine, ribavirin, and PGNNV-specific nanobody was constructed and designated as MWCNTs-PEI-R-Nb. Targeting ability and treatment effects of the MWCNTs-PEI-R-Nb were checked both in vitro and in vivo. MWCNTs-PEI-R-Nb showed an increasing distribution in PGNNV-infected cells, and an obvious accumulation in the brain of PGNNV-infected zebrafish larvae. MWCNTs-PEI-R-Nb also showed a strong anti-PGNNV ability both in vitro and in vivo. The mortality of larvae treated with MWCNTs-PEI-R-Nb (equivalent to 100 mg/L ribavirin) was 27% during 10 days post infection, whereas it was 100% for the control group. The results so far indicate that MWCNTs conjugated with antiviral drugs and viral-specific antibody are effective means for virus-induced CNS disease targeted therapy.

Using as an experimental model, the potential toxicity of graphene oxide (GO) was evaluated following exposure to 0-600 mg L for 24 h. The results showed that cell proliferation was observably inhibited and the IC value was 352.704 mg L. Mortality showed a concentration-dependent increase, and was 19.3% at 600 mg L. A small number of cells were deformed and shrunken after exposure. The percentage of late apoptosis/necrosis showed a significant increase ( 0.01) at 600 mg L (19.16%) compared with the control (1.14%). The mitochondrial transmembrane potential was significantly decreased ( 0.01) at 50-600 mg L, indicating that the apoptosis was related to mitochondrial impairment. Moreover, ROS was observably increased ( 0.01) at 200, 400 and 600 mg L. The expressions of apoptosis-related genes (SOD, Yca1, Nma111 and Nuc1) were significantly changed. The results presented so far indicate that GO has the potential to cause adverse effects on organisms when released into the environment.