Identification of the Bcl-2 family protein gene BOK from orange-spotted grouper (Epinephelus coioides) involved in SGIV infection

•Ec-BOK was cloned from orange-spotted grouper, Epinephelus coioides.•Ec-BOK distributed in all examined tissues.•Ec-BOK was up-regulated after SGIV infection in vitro.•Over-expression of Ec-BOK decreased virus replication in vitro.

Apoptosis plays vital roles in many physiological process and immune response. BOK is one of the central regulators in apoptosis. In this study, a new BOK homolog (Ec-BOK) was cloned and characterized from Orange-spotted grouper, Epinephelus coioides. Ec-BOK encoded a 210 amino acid peptides which shared 97% identity to Stegastes partitus BOK protein, contained four BH domains and one transmembrane region. Ec-BOK widely expressed in all analyzed tissues with the higher expressions in kidney and spleen. Its expression level was up-regulated after SGIV infection in vitro. Further analysis revealed that overexpression of Ec-BOK inhibited viral genes transcriptions and virus replication in fish cell. Our findings suggested that Ec-BOK might play a role in the immune response against virus.