Difference in medication pattern potentially enhances antiviral efficiency of a novel amino-fluorophenyl compound on WSS risk in shrimp seedling culture

Abstract

As an important upstream industry of prawn farming, shrimp seedling culture is extremely vulnerable to serious losses related to the unrestrained outbreak of white spot syndrome (WSS). The incomplete innate immune system of shrimp larvae may contribute to the difficulty in containing the spread of the virus with most treatment strategies. In order to solve this dilemma, in this study, we designed, synthesized and screened 2-amino-4-(4-fluorophenyl)-5-oxo-4H,5H-pyrano[3,2-c]chromene-3‑carbonitrile (C5) from our molecule drug library to seek its appropriate application in shrimp seedling culture. After evaluation on the anti-White Spot Syndrome Virus (WSSV) activity in Litopenaeus vannamei larvae, C5 was regarded as a promising anti-WSSV medicine with a maximum antiviral rate > 93% and significantly decreased 60% mortality of WSSV-infected larvae in a dose-dependent manner at 72 h post-infection (hpi). When WSSV was pre-incubated with 10 mg/L of C5 for 1–4 h, viral infectivity was greatly weakened by a lower lethality up to 58% at 144 hpi. In view of antiviral stability of C5 in aquacultural water within 2 days, continuous C5 exchange was performed, suggesting an obvious decrease of viral load and the increased survival of WSSV-infected larvae up to 50% at 144 hpi. Interestingly, continuous water exchange also contributed to improve the survival rate, which was necessary for shrimp larvae to eliminate excess organic pollutants. These results suggest that C5 hold potential for the treatment of WSSV infection in shrimp seedling culture.