BACKGROUND The domestic cat (Felis catus) is an important companion animal and is used as a large animal model for human disease. However, the comprehensive study of adaptive immunity in this species is hampered by the lack of data on lymphocyte antigen receptor genes and usage. The objectives of this study were to annotate the feline T cell receptor (TR) loci and to characterize the expressed repertoire in lymphoid organs of normal cats using high-throughput sequencing. RESULTS The Felis catus TRG locus contains 30 genes: 12 TRGV, 12 TRGJ and 6 TRGC, the TRB locus contains 48 genes: 33 TRBV, 2 TRBD, 11 TRBJ, 2 TRBC, the TRD locus contains 19 genes: 11 TRDV, 2 TRDD, 5 TRDJ, 1 TRDC, and the TRA locus contains 127 genes: 62 TRAV, 64 TRAJ, 1 TRAC. Functional feline V genes form monophyletic clades with their orthologs, and clustering of multimember subgroups frequently occurs in V genes located at the 5' end of TR loci. Recombination signal (RS) sequences of the heptamer and nonamer of functional V and J genes are highly conserved. Analysis of the TRG expressed repertoire showed preferential intra-cassette over inter-cassette rearrangements and dominant usage of the TRGV2-1 and TRGJ1-2 genes. The usage of TRBV genes showed minor bias but TRBJ genes of the second J-C-cluster were more commonly rearranged than TRBJ genes of the first cluster. The TRA/TRD V genes almost exclusively rearranged to J genes within their locus. The TRAV/TRAJ gene usage was relatively balanced while the TRD repertoire was dominated by TRDJ3. CONCLUSIONS This is the first description of all TR loci in the cat. The genomic organization of feline TR loci was similar to that of previously described jawed vertebrates (gnathostomata) and is compatible with the birth-and-death model of evolution. The large-scale characterization of feline TR genes provides comprehensive baseline data on immune repertoires in healthy cats and will facilitate the development of improved reagents for the diagnosis of lymphoproliferative diseases in cats. In addition, these data might benefit studies using cats as a large animal model for human disease.

中文翻译：

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Felis catus T细胞受体基因座的拓扑结构和表达库。

背景技术家猫（Felis catus）是重要的伴侣动物，并被用作人类疾病的大型动物模型。然而，由于缺乏关于淋巴细胞抗原受体基因和用途的数据，对该种适应性免疫的综合研究受到了阻碍。这项研究的目的是使用高通量测序来注释猫T细胞受体（TR）基因座，并表征正常猫的淋巴器官中表达的库。结果Felis catus TRG基因座包含30个基因：12个TRGV，12个TRGJ和6个TRGC，TRB基因座包含48个基因：33个TRBV，2个TRBD，11个TRBJ，2个TRBC，TRD基因座包含19个基因：11个TRDV，2个TRDD ，5个TRDJ，1个TRDC，而TRA位点包含127个基因：62个TRAV，64个TRAJ，1个TRAC。功能性猫V基因与其直系同源物形成单系进化枝，并且多成员亚群的聚集经常发生在位于TR基因座5'端的V基因中。功能性V和J基因的七聚体和九聚体的重组信号（RS）序列高度保守。分析TRG表达的库显示，盒内优先于盒间重排和TRGV2-1和TRGJ1-2基因的主要用途。TRBV基因的使用显示出较小的偏差，但第二个JC集群的TRBJ基因比第一个集群的TRBJ基因更常见地被重排。TRA / TRD V基因几乎只在其基因座内重排为J基因。TRAV / TRAJ基因的使用相对平衡，而TRD库由TRDJ3主导。结论这是猫中所有TR基因座的第一个描述。猫TR基因座的基因组组织与先前描述的颌骨脊椎动物（gnathostomata）相似，并且与进化的生死模型兼容。猫TR基因的大规模表征为健康猫的免疫库提供了全面的基线数据，并将有助于开发用于诊断猫淋巴增生性疾病的改良试剂。此外，这些数据可能有益于将猫用作人类疾病的大型动物模型的研究。猫TR基因的大规模表征为健康猫的免疫库提供了全面的基线数据，并将有助于开发用于诊断猫淋巴增生性疾病的改良试剂。此外，这些数据可能有益于将猫用作人类疾病的大型动物模型的研究。猫TR基因的大规模表征为健康猫的免疫库提供了全面的基线数据，并将有助于开发用于诊断猫淋巴增生性疾病的改良试剂。此外，这些数据可能有益于将猫用作人类疾病的大型动物模型的研究。