Inactivation of Red Sea Bream Iridovirus under Physical Conditions and Disinfectant Treatments

Red sea bream iridovirus (RSIV) causes substantial economic losses in net-pen mariculture. In this study, we evaluated the inactivation characteristics of RSIV under various physical conditions and disinfectant treatments to inform the implementation of appropriate hygiene management practices on fish farms. More than 90% of virus infectivity declined under the following physical conditions: exposure to natural seawater for 7 days, exposure to sunlight for 1 h, drying for 60 days, heating at 50°C for 30 min, or heating at 60°C for 30 s. These results indicate that appropriate hygiene management using effective disinfectants is important for preventing disease transmission. The present study demonstrated that the following disinfectant treatments achieved complete RSIV inactivation (>99.9%): 40% ethanol for 30 s, 0.5 ppm sodium hypochlorite for 30 s, 0.14 ppm free chlorine in electrolyzed seawater for 60 min, and 0.1% benzalkonium chloride for 30 s. When disinfectant solutions were prepared with seawater containing 10% organic matter (cell culture medium), 100 ppm sodium hypochlorite was required to ensure the rapid and complete inactivation of RSIV. Our findings provide fundamental information for the establishment of effective disinfection protocols to prevent RSIV transmission in semi-open system aquaculture.