Development and Efficacy Determination of an Attenuated Vaccine Against Channel Catfish Virus

Catfish aquaculture is the largest domestic sector of the U.S. aquaculture industry. Intensive aquaculture production systems are vulnerable to infectious disease outbreaks, resulting in significant economic losses. Catfish herpesviruses cause substantial mortality in catfish fry and fingerlings. Channel catfish virus (CCV) causes acute hemorrhagic infection and mortalities in catfish during the hatchery and nursery phases of production. Considering the key role of the catfish industry in U.S. aquaculture, it is imperative to control disease-related fish losses. Vaccines are considered the most effective proactive disease management strategy against viral infections. An attenuated CCV vaccine was developed by serial subculturing (P41) of the wild-type virus in channel catfish ovary (CCO/BB) cell cultures. This attenuated vaccine was administered via immersion to channel and hybrid catfish fingerlings. Thirty days post-immunization, the immunized and non-immunized fish were exposed to wild-type CCV. The percent survival was significantly higher in the immunized channel (96%) and hybrid (98%) catfish compared to the non-immunized group, confirming the protective immunity conferred by the attenuated vaccine. Initial trials suggest that the attenuated CCV vaccine developed in this study was found to be efficacious in reducing CCV-associated mortalities in catfish fingerlings. Further trials are needed to assess the safety of the vaccine.