Viral co-infection was documented in some fish diseases (Kokawa
et al., 2008; Lopez-Jimena et al., 2010; Tao et al., 2009). However,
the co-infection of megalocytivirus and VNNV in outbreaks of fish
diseases has not yet been reported. In the present study, we first
confirmed the coexistence of megalocytivirus and VNNV in a mass
mortality of juvenile orange-spotted groupers. A megalocytivirus was
then isolated and characterized using the MFF-1 cell line.