猪T细胞受体β链CDR3的多样性及其分子结构的遗传特征

Diversity and molecular genetic characteristics of porcine T cell receptor β chain CDR3

通过带谱分型技术研究临床健康猪T细胞受体(TCR)β链CDR3的谱型种类及多样性,并对其序列进行生物信息学分析,以探究CDR3分子结构的遗传特征。结果显示,20个TRBV家族在3头猪中均有表达,且大部分TRBV家族CDR3的谱型呈现类高斯分布,具有丰富的多样性;同一个体中不同TRBV家族CDR3出现的频次相差较大,同一TRBV家族在不同个体中出现的频次也不相同;100多条猪TCRβ链基因序列的CDR3分析发现,其大小在33~66nt之间,出现频次最多的序列为第42位碱基;在CDR3核苷酸序列组成中,鸟嘌呤的含量较高,推测其编码甘氨酸的频次较高;TCRβ链CDR3的两侧由相对保守的氨基酸组成,中间部分氨基酸变化较大,其中在第5位和第8位的氨基酸组成差异最大,确认CDR3的多样性和复杂性主要由D区两端的N插入序列及拼接时的灵活性造成。本研究结果为T细胞TCR分子的功能复杂性与特异性研究提供了一定的理论依据。

The immunoscope spectratyping technique was used to study diversity of TRBV complementarity determing region 3(CDR3)in health pigs and their sequences were analyzed by bioinformatics to study the molecular genetic characteristics of CDR3.In result,all of the 20TRBV families were expressed in 3 pigs,and CDR3 spectratyping of the most TRBV families showed a Gussian distribution with abundant diversities.The expression frequencies of these TRBV families were various among individuals while the variance also existed in the same TRBV family among distinct individuals.The size of TRB CDR3 was 33-66nucleotides with the prevalence of 42 nucleotides sequences discovered by analyzing over 100 sequences of TRB.Among the nucleotides of CDR3,guanine nucleotide and the deduced glycine were much prevalent.The deduced amino acid sequences of CDR3 were relatively conserved at both ends,but quite different in the center of it with most varibale amino acids at 5th and 8th sites.Furthermore,the junctional flexibility and N-region nucleotide addition were keys to generate the complexity and diversity of CDR3.In conclusion,these results could lay the theoretical foundation for the further researching on the functional complexity and specificity of TCRs on porcine T cells.