Antiviral effect of prodigiosin isolated from fish intestinal bacteria against Micropterus salmoides rhabdovirus

Micropterus salmoides rhabdovirus (MSRV) is the most lethal viral pathogen in largemouth bass farming, espe-cially threatening the health and survival of bass fry. However, there are still no specific commercialized drugs or vaccines to control MSRV infection. In this study, we identified a red-pigmented bacterial strain from the gut of M. salmoides, Serratia marcescens MS01. Interestingly, we found the methanol extracts of sediment (SED) of S. marcescens MS01 showed highly efficient anti-MSRV activity. SED effectively reduced the virulence of MSRV at a concentration of 30 mg/L, while the inhibition rate of glycoprotein and nucleoprotein expression of MSRV reached 99% in GCO cells. Besides, SED inhibited MSRV-induced oxidative stress and increased the activity of antioxidant enzyme in SOD and CAT. Subsequently, further purification, activity analysis, and multi -spectroscopic identification indicated prodigiosin played a crucial role in inhibiting MSRV in SED. Altogether, our finding suggests that SED or prodigiosin has the potential to be useful as a promising antiviral strategy against MSRV in aquaculture farms.