Establishment of an Infectious Hematopoietic Necrosis Virus (IHNV)-resistant Rainbow Trout Strain by Repetition of Selective Breeding Based on Artificial Infection

Abstract

To reduce losses induced by infectious hematopoietic necrosis (IHN), selective breeding of rainbow trout Oncorhynchus mykiss strains was conducted using artificial infection with the IHN virus (IHNV) TK8901, which was isolated in 1989. ​The cumulative mortality rate of the artificially infected rainbow trout strain decreased after successive rounds of selective breeding, reaching less than 5% from the 8th generation of selection. ​The cumulative mortality rate of the 9th generation of this strain infected with IHNV isolated in Tokyo in 2016 was significantly lower than that of the unselected strain. ​These results indicate that, after the 8th generation, rainbow trout strains that have survived from artificial infection have become resistant to IHNV infection.