Grouper is an important marine aquaculture species in Southeast Asian countries because of its fast growth, high disease resistance, rich nutrition, popular taste and high economic value (Harikrishnan et al., 2010). Intensive high-density farming of grouper has resulted in the outbreak of numerous infectious diseases, including viral disease; among them, nervous necrosis virus (NNV) infection can lead to vacuolation of the tissues in the central nervous system, and viral nervous necrosis (VNN), which cause mass mortality in grouper farming especially in larval stages with a mortality up to 100% (Costa & Thompson, 2016). NNV belongs to the family Nodaviridae, and it is