Antiviral activity of isoliquiritigenin against SVCV in aquaculture: A dual approach of immune modulation and viral inhibition

Isoliquiritigenin, a flavonoid from Glycyrrhiza glabra , demonstrates potent antiviral properties by enhancing host defenses through antioxidative and immunomodulatory mechanisms. Our in vitro data demonstrate that isoliquiritigenin significantly inhibits spring viremia of carp virus (SVCV) at concentrations up to 100 μg/ml without inducing cytotoxicity, effectively reducing viral replication and the production of new viral particles. Treatment with isoliquiritigenin markedly reduced the cytopathic effects in EPC cells, improving cell viability by more than 50 %. Furthermore, isoliquiritigenin enhances resistance to SVCV infection by significantly reducing intracellular the viral load when cells are pretreated for up to 24 h. This inhibition primarily occurs during the viral replication and assembly phases, without affecting viral binding or entry. Additionally, isoliquiritigenin strengthens antioxidant defenses and modulates immune responses, thereby reducing oxidative damage and interferon production. In vivo experiments with juvenile carp corroborate the antiviral efficacy of isoliquiritigenin, showing significantly reduced mortality rates and the viral load in SVCV-infected fish. These findings highlight the potential of isoliquiritigenin as an antiviral agent in aquaculture, providing a sustainable alternative to traditional chemotherapeutics by concurrently inhibiting viral replication and enhancing host immune defenses.