Institut de Biologie, Université de Neuchâtel, Neuchâtel, Switzerland.
Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland.
Sci Rep. 2019 Apr 30;9(1):6711. doi: 10.1038/s41598-019-43160-3.
The study of polymorphic immune genes in host populations is critical for understanding genetic variation in susceptibility to pathogens. Controlled infection experiments are necessary to separate variation in the probability of exposure from genetic variation in susceptibility to infection, but such experiments are rare for wild vertebrate reservoir hosts and their zoonotic pathogens. The bank vole (Myodes glareolus) is an important reservoir host of Borrelia afzelii, a tick-borne spirochete that causes Lyme disease. Bank vole populations are polymorphic for Toll-like receptor 2 (TLR2), an innate immune receptor that recognizes bacterial lipoproteins. To test whether the TLR2 polymorphism influences variation in the susceptibility to infection with B. afzelii, we challenged pathogen-free, lab-born individuals of known TLR2 genotype with B. afzelii-infected ticks. We measured the spirochete load in tissues of the bank voles. The susceptibility to infection with B. afzelii following an infected tick bite was very high (95%) and did not differ between TLR2 genotypes. The TLR2 polymorphism also had no effect on the spirochete abundance in the tissues of the bank voles. Under the laboratory conditions of our study, we did not find that the TLR2 polymorphism in bank voles influenced variation in the susceptibility to B. afzelii infection.
研究宿主群体中多态免疫基因对于理解病原体易感性的遗传变异至关重要。为了将暴露的可能性的变异与感染易感性的遗传变异分开，有必要进行受控感染实验，但对于野生动物的储存宿主及其人畜共患病原体来说，这样的实验很少见。田鼠（Myodes glareolus）是伯氏疏螺旋体（Borrelia afzelii）的重要储存宿主，伯氏疏螺旋体是一种引起莱姆病的蜱传螺旋体。田鼠种群在 Toll 样受体 2（TLR2）上存在多态性，TLR2 是一种先天免疫受体，可识别细菌脂蛋白。为了测试 TLR2 多态性是否影响对伯氏疏螺旋体感染的易感性的变化，我们用感染伯氏疏螺旋体的蜱挑战了无病原体、已知 TLR2 基因型的实验室出生的个体。我们测量了田鼠组织中的螺旋体负荷。受感染蜱叮咬后的伯氏疏螺旋体感染易感性非常高（95%），并且在 TLR2 基因型之间没有差异。TLR2 多态性也对田鼠组织中的螺旋体丰度没有影响。在我们研究的实验室条件下，我们没有发现田鼠 TLR2 多态性影响伯氏疏螺旋体感染易感性的变化。
