Influence of temperature on Betanodavirus infection in Senegalese sole (Solea senegalensis)

In this study Senegalese sole juveniles were experimentally infected with a reassortant Betanodavirus strain at three different temperatures: 22 degrees C, 18 degrees C and 16 degrees C by bath challenge and cohabitation. The results obtained showed that virus virulence decreased by reducing the water temperature. At 22 degrees C mortalities reached 100%, at 18 degrees C they ranged from 75 to 80% and at 16 degrees C only 8% of the fish died. In addition, horizontal transmission was demonstrated regardless of the rearing temperature. At 16 degrees C active viral replication was detected up to 66 days post-infection, but no signs of the disease were observed and only a very low level of mortality was recorded. The increase in water temperature from 16 to 22 degrees C caused a quick rise in the viral load and a subsequent outbreak of mortalities. These findings demonstrate that this reassortant Betanodavirus strain can cause a persistent infection in Senegalese sole at low temperatures (16 degrees C) for long periods of time, and when temperature increases the virus is able to trigger an acute infection and provoke high mortalities. (C) 2015 Elsevier B.V. All rights reserved.