Abstract
Spring viremia of carp virus (SVCV) is a significant pathogen that has notably hindered the advancement of cyprinid aquaculture in recent years. Infections caused by SVCV are often associated with substantial economic losses due to the absence of effective treatment options. Previous reports indicated that N-(4-methyl-2-oxo-2H-chromen-7-yl) benzenesulfonamide (N6) exhibits inhibitory effects on SVCV proliferation. This study aims to comprehensively evaluate the anti-SVCV effects of N6 using healthy young carp as the experimental model. The research investigates the antiviral activity of this compound in vivo, the immune response of interferon (IFN)-related genes, its impact on the horizontal transmission of SVCV, and histopathological changes. The results indicate that N6 significantly inhibits SVCV infectivity and apoptosis in EPC cells in vitro. Furthermore, while N6 reduced horizontal transmission of SVCV in a static cohabitation challenge model, the N6-treated SVCV-infected group showed a nearly 3-fold decrease in viral load compared to the control group, it did not completely prevent transmission at established antiviral dosages. Histopathological analysis of the affected fish revealed that N6 effectively mitigated tissue damage induced by SVCV. Additionally, the up-regulation of six IFN-related genes suggests that N6 may indirectly activate IFNs to facilitate the clearance of SVCV in the kidney and spleen, as demonstrated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). These findings provide a foundation for further investigations into the mechanisms by which N6 acts against SVCV and may aid in the development of novel anti-SVCV therapeutics.