Objective Functions of pellino E3 ubiquitin protein ligase 2 gene (peli2) in the innate immune system of Danio rerio were investigated to facilitate studies on the immunological mechanisms in aquatic species and other vertebrates.

Methods The fragment of zebrafish peli2 was cloned via the reverse transcription PCR. Multiple sequence alignment and phylogenetic analyses were conducted using Clustal Omega and MEGA X software. Applying qRT-PCR, expressions in different zebrafish organs as well as embryonic fibroblast cell line (ZF4) after stimulation with lipopolysaccharide (LPS), polyinosinic-polycytidylic acid poly(I:C), and spring viremia of carp virus (SVCV) were determined.

Results Zebrafish peli2 contained 1 287 bp ORF encoding 428 amino acids. Phylogenetically, it showed high sequence conservation with 84%–88% similarity with Homo sapiens, Rattus norvegicus, Xenopus laevis, and Cololabis saira. The constitutive expression was observed across all examined organs, with significantly higher levels in the renal and branchial than the cardiac and ocular tissues. And it was regulated by the immune stimulus encountered.

Conclusion The expression of zebrafish peli2 was rich in immune-responsive organs, such as kidney, gill, and spleen. It varied significantly by the inducing stimuli suggesting a crucial role it played in the innate immunity of zebrafish. Due to the evolutionary conservation with other vertebrates, peli2 could turn the fish into a translational model for studies on peli2-associated diseases in humans.