Susceptibility of Ictavirus acipenseridallo2 , White Sturgeon iridovirus, and ranaviruses to buffered povidone iodine complex, chlorine, and Virkon Aquatic

Ictavirus acipenseridallo2 (AciHV-2), White Sturgeon iridovirus (WSIV), Ranavirus rana1 (RR1), and Ranavirus alytes1 (RA1) are important viral pathogens of cultured sturgeon. The purpose of this study was to identify the virucidal efficacy of household bleach (free chlorine), a buffered povidone iodine complex (PVP iodine), and Virkon Aquatic, against these important sturgeon pathogens. The viruses were grown in White Sturgeon skin (AciHV-2 and RA1), White Sturgeon spleen (WSIV), or epithelioma papulosum cyprini (RR1) cell lines, and in vitro susceptibility to free-chlorine, PVP iodine, and Virkon Aquatic was investigated. Virucidal reductions in titer >4 log10 TCID50/mL (>99.99% reduction) for AciHV-2 were obtained with 25 mg/L free chlorine after 10 min but immediately with 100 mg/L. Similarly, virucidal reductions for WSIV were obtained with 100 mg/L free chlorine immediately. Virucidal reductions for RA1 were obtained with 500 mg/L free chlorine, but RR1 persisted even after incubation with 500 mg/L free chlorine for 1 h. PVP iodine inactivated AciHV-2 after 30 min of incubation in 50 mg/L. White Sturgeon iridovirus was inactivated immediately after incubation in 50 mg/L PVP iodine. Although RA1 was inactivated after a 30-min incubation in 50 mg/L PVP iodine, RR1 isolates still persisted in 50 mg/L PVP iodine after 30 min. Among the disinfectants that were tested, Virkon Aquatic was the most consistent and effective, inactivating AciHV-2, WSIV, and the two ranaviruses immediately at the recommended concentration of 0.5%. The information presented in this study should be taken into consideration when developing biosecurity protocols in captive sturgeon programs to prevent the spread of these important viruses.