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CD80是T细胞活化和增殖过程中不可缺少的膜抗原,为T细胞的增殖分化提供必要的共刺激信号,在特异性细胞免疫过程中具有重要作用。本研究从罗非鱼脾脏组织中克隆获得CD80基因的编码区序列(Gen Bank登录号:KU884324;命名为On-CD80),该基因全长810 bp,可编码269个氨基酸,理论分子量为29.83 k D,等电点为5.97。氨基酸序列分析显示On-CD80具有2个保守的免疫球蛋白样结构域(Ig-like domain),5’端有一个典型的信号肽序列,3’端具有1个跨膜结构域。系统进化树中罗非鱼与伯氏朴丽鱼CD80蛋白聚为一支,显示了较高的同源性。荧光定量PCR分析显示,On-CD80在健康尼罗罗非鱼组织中均有表达,且在脾脏组织中表达量最高。经灭活的无乳链球菌免疫后,On-CD80在肾脏、脾脏、胸腺、肠道、鳃、脑组织中的表达量均显著上调,且表现出较为明显的时间依赖性表达模式,肠道、鳃和脑分别在8 h、24 h出现表达高峰,并于48 h、96 h再次出现表达高峰。脾脏和肾脏、胸腺的On-CD80表达则分别是在48 h、72 h达到表达高峰。综上所述,On-CD80表达能被无乳链球菌所诱导,提示该分子可能参与罗非鱼的抗菌免疫应答,该结果为进一步研究On-CD80在罗非鱼感染无乳链球菌过程中的作用奠定了一定的基础。
CD80 is an essential membrane antigen in the process of T cell activation and proliferation. It provides necessary co-stimulatory signals for the proliferation and differentiation of T cells, and plays an important role in specific cellular immunity. This study cloned the coding region of CD80 gene (GenBank accession number: KU884324; named On-CD80) from the tilapia tissue of tilapia. The full length of this gene was 810 bp and encodes 269 amino acids with a theoretical molecular weight of 29.83 k D, isoelectric point of 5.97. Amino acid sequence analysis showed that On-CD80 has two conserved immunoglobulin-like domains (Ig-like domain), 5 ’end has a typical signal peptide sequence, 3’ end has a transmembrane domain. Phylogenetic tree of tilapia and berry primate CD80 protein together, showing a high homology. Quantitative real-time PCR analysis showed that On-CD80 was expressed in healthy Nile tilapia tissues and highest in spleen tissues. On-CD80 expression in kidney, spleen, thymus, gut, gill and brain tissue was significantly up-regulated after inactivated Streptococcus agalactiae inactivated, and showed a more obvious time-dependent expression pattern. Intestinal , Gill and brain peaked at 8 h and 24 h, respectively, and peaked again at 48 h and 96 h. Spleen and kidney, the expression of On-CD80 in the thymus reached the peak at 48 h and 72 h, respectively. In summary, On-CD80 expression can be induced by Streptococcus agalactiae, suggesting that the molecule may be involved in the antibacterial immune response of tilapia, the results for further study of On-CD80 in tilapia infected with Streptococcus agalactiae The role of lay a solid foundation.