Detection of Erythrocytic Inclusion Body Syndrome (EIBS) Virus (Piscine orthoreovirus 2) from Ovarian Fluid of Coho Salmon Survivor

Abstract

Mortality of farmed coho salmon Oncorhynchus kisutch due to erythrocytic inclusion body syndrome (EIBS) has been posing severe economic losses in Japan since 1986. The etiologic agent of EIBS was reported to be piscine orthoreovirus 2 (PRV-2). We detected PRV-2 in the ovarian fluid samples of 10% of EIBS-experienced spawners (n = 30) by RT-PCR. When each of 30 individual ovarian fluid samples was inoculated into a naïve coho salmon, 37% of the blood samples from the fish tested positive for PRV-2 at 20 days post injection. These observations suggest that the ovarian fluid of EIBS-experienced fish can be contaminated with the infective viral particles of PRV-2.