The Differential Evolutionary Dynamics of Avian Cytokine and TLR Gene Classes
The Differential Evolutionary Dynamics of Avian Cytokine and TLR Gene Classes
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DOI：
10.4049/jimmunol.0903092
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发表时间：
2010-06-15
影响因子：
4.4
通讯作者：
Bradley, Daniel G.
中科院分区：
文献类型：
--
作者：
Downing, Tim;Lloyd, Andrew T.;Bradley, Daniel G.
测序能力的最新进展大大增强了研究免疫基因多样性的潜力。在这项研究中，使用高通量测序检查了两类具有不同功能作用、病原体检测和免疫机制介导的禽类免疫基因的变异。 TLR 通过检测病原微生物中保守的分子基序来识别和警告免疫系统，而细胞因子则充当炎症和免疫的介质。对一组家鸡和野生原鸡 (JF) 中每个类别的 9 个基因进行了重新测序。对基因类别之间的人群范围遗传变异的测试表明，每组的等位基因频谱都是独特的。 TLR 显示了指向定向选择的证据，而细胞因子的信号更提示频率依赖性选择。仅考虑编码位点的分布之间仍然存在这种差异，表明功能相关性。每个基因类别的独特变异模式可能受到它们在免疫反应中不同功能作用的限制。 TLR 可识别数量相对有限的外源致病相关模式，并且需要快速适应以应对新环境中遇到的不断进化的新型微生物。相反，细胞因子与许多分子相互作用，介导免疫机制的力量，并相应地对许多传染病的选择性刺激做出反应。分析还表明，鸡和红 JF 之间、鸡和灰 JF 之间 TLR1LA 和 TLR2A 的广泛遗传交换增强了高变异性的一般模式。免疫学杂志，2010，184：6993-7000。
The potential for investigating immune gene diversity has been greatly enhanced by recent advances in sequencing power. In this study, variation at two categories of avian immune genes with differing functional roles, pathogen detection and mediation of immune mechanisms, was examined using high-throughput sequencing. TLRs identify and alert the immune system by detecting molecular motifs that are conserved among pathogenic microorganisms, whereas cytokines act as mediators of resulting inflammation and immunity. Nine genes from each class were resequenced in a panel of domestic chickens and wild jungle fowl (JF). Tests on population-wide genetic variation between the gene classes indicated that allele frequency spectra at each group were distinctive. TLRs showed evidence pointing toward directional selection, whereas cytokines had signals more suggestive of frequency-dependent selection. This difference persisted between the distributions considering only coding sites, suggesting functional relevance. The unique patterns of variation at each gene class may be constrained by their different functional roles in the immune response. TLRs identify a relatively limited number of exogeneous pathogenic-related patterns and would be required to adapt quickly in response to evolving novel microbes encountered in new environmental niches. In contrast, cytokines interact with many molecules in mediating the power of immune mechanisms, and accordingly respond to the selective stimuli of many infectious diseases. Analyses also indicated that a general pattern of high variability has been enhanced by widespread genetic exchange between chicken and red JF, and possibly between chicken and gray JF at TLR1LA and TLR2A. The Journal of Immunology, 2010, 184: 6993-7000.