猪T细胞受体β链的基因结构及其多样性分析

Genetic Structure and Diversity of Porcine T Cell Receptor β Chain Genes

设计猪TCRβ链基因的一对特异性引物,用RT-PCR法从合作小型猪外周血、淋巴结和脾淋巴细胞中高通量克隆和鉴定了82个猪TCRβ基因(简称STB)。测序分析表明,克隆的猪TCRβ链的基因都含有可变的信号肽区和V区、高变的D区和J区以及恒定的C区的基因片段,绝大部分基因间的核苷酸序列组成都不完全相同,且具有十分复杂的多态性和多样性,基因间的相似性在36.6%~99.9%,这与TCRβ链的基本基因结构特征相一致。猪TCRβ基因的分子结构、遗传演化关系和归类分析发现,在同一类基因分子中其信号肽区、FR1区和CDR1区、FR2区和CDR2区以及FR3区之间的差异主要由V基因片段的多态性引起,而CDR3区的差异主要由其D、J基因片段的多样性造成。同时发现猪TCRβ与人类的遗传演化关系较近,大部分基因序列都能找到与人类对应的TRBV、TRBD、TRBJ基因片段,但又存在一定的差异性。这表明,猪TCRβ基因既有应对外界复杂微生物环境的免疫多样性分子遗传基础,也有物种间的相似性与特异性。

Based on the gene of porcine T cell receptorβchain(TCRβ)from the GenBank database,82 of swine T cell receptorβchain genes(STB)were cloned by reverse transcription-polymerase chain reaction(RT-PCR)from porcine lymphocyte of peripheral-blood,lymphoid node and spleen with one pair primers.Sequence analysis showed that STBgenes were all contain a domain of variable signal peptide and V,hypervariable Dand J,and conservative Cdomain.However,nucleotide sequence of STB was not complete identical with 36.6%-99.9% homology among genes,and had extremely sophisticated polymorphism and diversity.This was concord to the genetic structure of TCRβchain.Molecular structure,genetic evolution and classify of porcine TCRβgenes displayed that mutations on the domain of signal peptide,FR1 and CDR1,FR2 and CDR2,as well as FR3 were caused by polymorphism of the STBV.And differences of CDR3 domain,however,were caused by diversity of the STBDand STBJ.Analysis of similarity and classify of TCRβV domain(STBV),Ddomain(STBD)and Jdomain(STBJ)of swine compared with human,found the genetic evolution relationship was closer,and each of TRBV,STBD and TRBJ also had a corresponding fragment of human.This indicated that pig possessed the genetic diversity ofimmunology against complicated environment of microbes in healthy status.