Comparison of Viral Replication, Antiviral Gene Expression and Antioxidant Enzyme Activity in Gibel Carp (Carassius auratus gibelio) Infected with Cyprinid Herpesvirus 2 at Susceptible and Less-susceptible Temperatures

Cyprinid herpesvirus 2 is a DNA virus that is a concern for the aquaculture worldwide. Here, the challenge of CyHV-2 infection was conducted in gibel carp at a host susceptible temperature (25 ℃) and a less-susceptible temperature (15 ℃). The viral replication and expression of antiviral genes were analyzed by real time PCR, and the activities of antioxidative enzymes in serum were also examined. Results showed that CyHV-2 was in normal proliferative in 25 ℃ group, while the growth was inhibited in 15 ℃ group. Moreover, IFNφ1 and Mx were highly expressed from 12 hpi to 48 hpi in both groups, but the 15 ℃ group showed quicker and stronger response. TNF-α and IL-1β showed early upregulation at 12 hpi followed by a sharp decline in both groups. Fatty acid synthase (FAS) and Caspase-8 showed a higher expression level in 15 ℃ group than that in 25 ℃ group during 48-96 hpi. Furthermore, the activities of antioxidant enzymes (SOD and CAT) in 15 ℃ group were higher than those in 25 ℃ group at late infection. Thus, water temperature affected the immune response against CyHV-2 infection, which may ultimately lead to host survival in the less-susceptible temperatures.