In-vitro administration of vitamin C solution induces multiple cellular mechanisms in common carp brain cells and carp-derived leukocytes, resisting infection by Koi herpesvirus

Infectious diseases in fish pose serious challenges for aquaculture due to limited availability of acceptable control measures. Recently, aquaculture health providers and researchers have shifted their attention toward more sustainable disease-preventive solutions. Probiotics use in fish diets has become widespread to increase feed efficiency and reduce disease risk. This study examined a proposed role of vitamin C (vitC) in mitigating infection caused by Koi herpesvirus (KHV) in vitro. Naïve and mitogen-stimulated carp-derived leukocytes and common carp brain cell line were treated with 25, 50, and 75 μg/mL sodium L-ascorbate 2 h before KHV challenge. Ascorbic acid was then readministered after 24 and 48 h in the same concentrations. Assessment of cell function for proliferation; detection of reactive oxygen species, apoptosis, and activity of caspases 8 and 9; and cell chemotaxis were performed after 24, 48, and 72 h. KHV load was quantified and its replication assessed. Results reveal that vitC plays cell protective regulatory and potentially virucidal roles against KHV infection depending upon cell type. VitC's mechanisms implicate both antioxidation and pro-oxidative enhancement of cell defense involving promotion of cell proliferation and/or cell apoptosis and directed cell chemotaxis migration. Antiviral activity was rather pronounced in leukocytes as viral genome copies decreased significantly. This study therefore indicates vitC to possess selective cell regulating machinery against koi herpesvirus infection in carp cells reflecting the disease-resistance influence reported in other teleosts. Further investigating vitC's role within the in vivo system could provide insights sufficient for implementing this nutrient into daily carp diets. •A proposed role of vitC in mitigating infection caused by koi herpesvirus in vitro is examined.•Oxidative burst suggests prooxidative function of vitC for pathogen killing.•Intrinsic apoptosis via casp-9 is likely a key mechanism in vitC's antiviral activity.•VitC potentiate KHV inhibition independently of the in-vitro replicative site (CCB).•The study demonstrates a cell-protective and immune supportive influence of vitC.