Potential prospect of a therapeutic agent against spring viraemia of carp virus in aquaculture

Spring viraemia of carp virus (SVCV) is an efficient and devastating pathogen in cyprinids, resulting in serious economic losses in aquaculture. Based on the previous results that 7-(3-benzimidazole propoxy) coumarin (B4) significantly inhibited SVCV replication in fish cells, we consider that B4 may be useful as a potential antiviral agent. In this study, when B4 was preincubated with SVCV, infectivity was significantly inhibited in vitro in a dose-time-dependent manner. Whilst B4 exhibited anti-SVCV effect in vivo via substantially enhancing survival rate of zebrafish and common carp (the maximum 40% increment) under both bath and injection treatments. Consistent with above results, B4 also significantly decreased the viral titer of survival and dead zebrafish in the early stage of virus infection, and was stable in water for a prolonged inhibitory half-life (about 4 days). Although horizontal transmission of SVCV was not completely blocked by B4 at the established antiviral doses, the viral loads were obviously reduced in donor and recipient fish under a static challenge co-habitation. Importantly, the results indicated that B4 partially inactivated the virus to induce an antiviral immune responses by the higher levels of IFNs expression, suggesting that a new useful protection may be performed for future vaccination approaches. Overall, B4 will be an excellent potential choice for the therapeutic agent against SVCV infection in aquaculture.