Data from: Polymorphisms at the innate immune receptor TLR2 are associated with Borrelia infection in a wild rodent population

The discovery of the key role of Toll-like receptors (TLRs) in initiating innate immune responses and modulating adaptive immunity has revolutionised our understanding of vertebrate defence against pathogens. Yet, despite their central role in pathogen recognition and defence initiation, there is little information on how variation in TLRs influences disease susceptibility in natural populations. Here we assessed the extent of naturally occurring polymorphisms at TLR2 in wild bank voles (Myodes glareolus) and tested for associations between TLR2 variants and infection with Borrelia afzelii, a common tick-transmitted pathogen in rodents and one of the causative agents of human Lyme disease. Bank voles in our population had 15 different TLR2 haplotypes (ten different haplotypes at the amino acid level), which grouped in three well-separated clusters. In a large-scale capture-mark-recapture study we show that voles carrying TLR2 haplotypes of one particular cluster (TLR2c2) were almost three times less likely to be Borrelia-infected than animals carrying other haplotypes. Moreover, neutrality tests suggested that TLR2 has been under positive selection. This is the first demonstration of an association between TLR polymorphism and parasitism in wildlife, and a striking example that genetic variation at innate immune receptors can have a large impact on host resistance.

关于Toll样受体（Toll-like receptors, TLRs）在启动固有免疫应答、调节适应性免疫中关键作用的发现，彻底革新了我们对脊椎动物对抗病原体防御机制的认知。尽管TLRs在病原体识别与防御启动中处于核心地位，但目前关于TLRs基因变异如何影响自然种群中宿主疾病易感性的研究仍较为匮乏。本研究对野生棕背䶄（Myodes glareolus）的TLR2基因自然存在的多态性程度进行了评估，并检验了TLR2变异体与阿氏包柔螺旋体（Borrelia afzelii）感染之间的关联——该病原体是啮齿类动物中常见的蜱传病原体，也是人类莱姆病的致病原之一。本研究种群中的棕背䶄共存在15种不同的TLR2单倍型（在氨基酸水平上可归为10种不同单倍型），可划分为3个清晰分离的簇。通过大规模标记重捕研究，我们发现携带某一特定簇TLR2单倍型（TLR2c2）的棕背䶄，其感染阿氏包柔螺旋体的概率仅为携带其他单倍型个体的约三分之一。此外，中性检验结果显示TLR2基因受到了正选择作用。本研究首次证实了野生动物种群中TLR多态性与寄生感染之间存在关联，同时也极具说服力地证明了固有免疫受体的遗传变异可对宿主抗性产生显著影响。