Evaluation on the antiviral activity of Bacillus velezensis extract against spring viremia of carp virus

Abstract

Spring viremia of carp virus (SVCV), a member of the family Rhabdoviridae, can cause acute haemorrhagic and contagious viraemia in cyprinids. In this study, the ethyl acetate extract from Bacillus velezensis JW supernatant (EJW) was explored for anti-SVCV activity in vitro and in vivo. EJW showed a highly efficient anti-SVCV activity with an inhibitory rate more than 95% at the concentration of 30 mg/L, and mainly inhibited the early events of SVCV replication (except adsorption) in epithelioma papulosum cyprini (EPC) cells. What's more, in the treatment of EJW, SVCV glycoprotein and nucleoprotein gene expression were significantly inhibited in kidney and spleen of common carps at 2 and 4 d, and the survival rate of SVCV-infected common carp was increased up to 14%. Furthermore, the expression levels of IFN-Ι, IFNφ2β, TNFα and MDA5 genes were up-regulated, which showed that EJW could enhance the expression of antiviral immune genes. Altogether, EJW is suggested as a promising antiviral strategy against SVCV and can be further explored for controlling the virus infection in aquaculture farms.