Susceptibility of different weight ranges of Epinephelus coioides to piscine nodavirus

Abstract

The susceptibility of different weight ranges of orange-spotted grouper (Epinephelus coioides) to piscine nodavirus was studied by experimental infection. Size ranges of 1-2 g, 6-8 g, 10-13 g, 30-60 g, and 90-120 g were intramuscularly injected with 50 µL 10⁶ TCID₅₀/mL of the cell culture supernatant. Clinical signs were observed and mortality occurred from 4 days post infection (dpi) for weight range 1-2 g to 7 dpi for weight range 30-60 g. Fish with weight ranges 1-2 g and 6-8 g showed highest susceptibility with mortality rate of 80% while fish with weight range 90-120 g were no longer susceptible. Mortality rates for weight ranges 10-13 g and 30-60 g were 50% and 20%, respectively. No mortality was observed in the 90-120 g weight range and the control group. These data show that the susceptibility of orange-spotted grouper to VNN is weight-dependent.