Center for Experimental and Molecular Medicine, Amsterdam Infection and Immunity, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Biology Centre, Institute of Parasitology, Czech Academy of Sciences, Ceske Budejovice, Czech Republic.
Sci Rep. 2020 Nov 18;10(1):20061. doi: 10.1038/s41598-020-76268-y.
Ixodes ricinus is the vector for Borrelia afzelii, the predominant cause of Lyme borreliosis in Europe, whereas Ixodes scapularis is the vector for Borrelia burgdorferi in the USA. Transcription of several I. scapularis genes changes in the presence of B. burgdorferi and contributes to successful infection. To what extend B. afzelii influences gene expression in I. ricinus salivary glands is largely unknown. Therefore, we measured expression of uninfected vs. infected tick salivary gland genes during tick feeding using Massive Analysis of cDNA Ends (MACE) and RNAseq, quantifying 26.179 unique transcripts. While tick feeding was the main differentiator, B. afzelii infection significantly affected expression of hundreds of transcripts, including 465 transcripts after 24 h of tick feeding. Validation of the top-20 B. afzelii-upregulated transcripts at 24 h of tick feeding in ten biological genetic distinct replicates showed that expression varied extensively. Three transcripts could be validated, a basic tail protein, a lipocalin and an ixodegrin, and might be involved in B. afzelii transmission. However, vaccination with recombinant forms of these proteins only marginally altered B. afzelii infection in I. ricinus-challenged mice for one of the proteins. Collectively, our data show that identification of tick salivary genes upregulated in the presence of pathogens could serve to identify potential pathogen-blocking vaccine candidates.
硬蜱是阿费尔通螺旋体（Borrelia afzelii）的传播媒介，是欧洲莱姆病的主要病原体，而肩突硬蜱（Ixodes scapularis）则是伯氏疏螺旋体（Borrelia burgdorferi）在美国的传播媒介。在伯氏疏螺旋体存在的情况下，几种肩突硬蜱基因的转录会发生变化，并有助于成功感染。阿费尔通螺旋体在硬蜱唾液腺中对基因表达的影响程度在很大程度上尚不清楚。因此，我们使用大规模 cDNA 末端分析（Massive Analysis of cDNA Ends，MACE）和 RNA 测序来测量感染前后未感染和感染的蜱唾液腺基因的表达，共定量了 26179 个独特的转录本。虽然蜱的取食是主要的区分因素，但阿费尔通螺旋体感染显著影响了数百个转录本的表达，包括在蜱取食 24 小时后有 465 个转录本。在 10 个具有不同遗传背景的生物学重复中，对蜱取食 24 小时时前 20 位阿费尔通螺旋体上调转录本进行验证，结果表明表达变化很大。其中 3 个转录本可以验证，它们是一个碱性尾部蛋白、一个脂钙蛋白和一个 ixodegrin，可能参与阿费尔通螺旋体的传播。然而，用这些蛋白的重组形式进行疫苗接种，仅能在一定程度上改变 I. ricinus challenged 小鼠中阿费尔通螺旋体的感染，其中一种蛋白的效果较为显著。总的来说，我们的数据表明，鉴定在病原体存在下上调的蜱唾液基因可以作为潜在的病原体阻断疫苗候选物。
