Molecular characterization and expression analysis of B-cell lymphoma-2 protein in Amphiprion clarkii and its role in virus infections

• Published in: Fish & shellfish immunology Vol. 130; pp. 206 - 214
• Main Authors: Madushani, K.P., Shanaka, K.A.S.N., Wijerathna, H.M.S.M., Lim, Chaehyeon, Jeong, Taehyug, Jung, Sumi, Lee, Jehee
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2022
• Subjects: Anti-apoptosis; Gene expression; Innate immunity; Molecular characterization; VHSV; Innate immunity; Anti-apoptosis; Molecular characterization; Gene expression; VHSV
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2022.09.005

Amphiprion clarkii is increasingly being used as a captive-bred ornamental fish in South Korea. However, its breeding has recently been greatly hindered by destructive diseases due to pathogens. B-cell lymphoma-2 (Bcl2), a mitochondrial apoptosis regulatory gene involved in immune responses, has not been investigated in anemonefish, including A. clarkii. Herein, we aimed to annotate Bcl2 in the A. clarkii transcriptome and examined its role against virus infections. Sequence analysis indicated that Bcl2 in A. clarkii (AcBcl2) contained all four Bcl-2 homology domains. The structure of AcBcl2 closely resembled those of previously analyzed anti-apoptotic Bcl2 proteins in mammals. Expression analysis showed that the highest level of AcBcl2 was expressed in blood. AcBcl2 expression in the blood was downregulated within 24 hpi when challenged with immune stimulants poly I:C and lipopolysaccharides. AcBcl2 reduced poly I:C-induced cell death. The propagation of viral hemorrhagic septicemia virus (VHSV) was higher in the presence of AcBcl2. Cell mortality was higher in AcBcl2 when transfected cells were infected with VHSV, and a higher viral transcript was observed compared to their respective controls. In conclusion, AcBcl2 is an anti-apoptotic protein, and its activity may facilitate the propagation of VHSV. •The Bcl-2 gene was identified and cloned from Amphiprion clarkii.•AcBcl-2 was highly expressed in blood, heart, and spleen, mediating host defense mechanisms.•Transcription of AcBcl-2 was modulated upon immune challenges.•The overexpressed AcBcl-2 increased the VHSV gene transcription.