IMGT Nomenclature and IMGT Numbering of the Grass Carp (Ctenopharyngodon idella) IGH Locus and Genes as a Paradigm for Cyprinoidei

The adaptive immune system of teleost fish is capable of producing a diverse array of antibodies to defend against pathogen invasion. The structural and typological diversity of these immunoglobulins reflects the evolution and specialization of immunoglobulins during the early stages of vertebrate evolution. Based on the standardized nomenclature established by the international ImMunoGeneTics information system® (IMGT®), this study successfully constructed the reference sequences of the immunoglobulin heavy chain (IGH) genes extracted from the HZGC01 assembly of grass carp (Ctenopharyngodon idella). This work involved the systematic annotation and delineation of the variable (V), diversity (D), joining (J), and constant (C) genes, following the IMGT biocuration pipeline including identification, description, classification, numerotation, orientation, and localization concepts. The RS consensus sequences and structural features of the upstream regions of V-REGION genes, including the 5′ UTR, L-PART1, and V-INTRON length, were also characterized. The constructed reference sequences provide a standardized molecular framework and a valuable genomic resource for comprehensive analysis of the grass carp antibody repertoire while also establishing a valuable paradigm for the standardized nomenclature and numbering of IGH genes in Cyprinoidei fishes.