DAO 146:1-8 (2021)  -  DOI: https://doi.org/10.3354/dao03615

ABSTRACT: Infectious hematopoietic necrosis virus (IHNV) is known as a causative agent of heavy mortalities in farmed rainbow trout. However, there is limited information on its virulence for marine fish species. In this study, Japanese amberjack Seriola quinqueradiata and red sea bream Pagrus major were experimentally infected by intraperitoneal (IP) injection and immersion, with an IHNV isolate from rainbow trout in Japan, to evaluate the virulence of the virus for these fish species. The cumulative mortality for immersed rainbow trout was 15%. IHNV was isolated from all dead fish and 50% of the sequentially sampled rainbow trout. When Japanese amberjack were challenged by IP injection and immersion, the resulting cumulative mortality was 70% and 0%, respectively. The virus was isolated from all dead fish and 1 out of 3 Japanese amberjack sampled at 9 d post exposure. However, no mortality was observed in either of the red sea bream groups challenged with IHNV. IHNV was not isolated from any of the surviving red sea bream, or from any of the sequentially sampled fish. The viral titer on Japanese amberjack-derived YTF cells was in the same log range as that on FHM and RTH-149 cells, but the titers on the red sea bream cell lines SBK and GBRS were lower than the other cell lines, and were significantly different from the FHM and RTH-149 cell lines. These results suggest that Japanese amberjack has a low susceptibility to IHNV, and red sea bream has no or little susceptibility to the virus.

KEY WORDS: Infectious hematopoietic necrosis virus · IHNV · Japanese amberjack · Red sea bream · Susceptibility