MacIntosh Grace Hadley, Nuyens Alexandra C, Vickery Jessica L, Berthold Anne, Lloyd Vett K
Dept. Biology, Mount Allison University, Sackville, New Brunswick, Canada.
PLoS One. 2025 Jun 5;20(6):e0324546. doi: 10.1371/journal.pone.0324546. eCollection 2025.
Borrelia burgdorferi, a tick-vectored spirochete bacteria best known for causing Lyme disease, has been found to induce physiological and behavioural changes in its tick vector that can increase tick fitness and its ability to transmit the bacteria. The mechanism by which this bacterium modulates these changes remains unknown. Epigenetics plays a central role in transducing external and internal microbiome environmental influences to the organism, so we investigated DNA methylation and the expression of a key histone modification enzyme in Borrelia-infected and uninfected Ixodes scapularis ticks. DNA methylation of the pericentromeric tandem repeats family, Ixodes scapularis Repeats (ISR), were assessed by methylated-DNA immunoprecipitation (MeDIP) followed by qPCR of the ISR regions. DNA methylation of the ISR sequences was found. The different repeats had different levels of DNA methylation, however, these levels were not significantly affected by the presence or absence of B. burgdorferi. The epigenetic regulator euchromatic histone lysine methyltransferase 2 (EHMT2) is recognized as having a key role in modulating the organismal stress response to infections. To assess EHMT2 transcription in Borrelia-infected and uninfected ticks, real-time reverse transcriptase PCR was performed. Uninfected ticks had over 800X lower EHMT2 expression than infected ticks. This study is among the first to identify a gene that may be involved in producing epigenetic differences in ticks depending on infection status and lays the groundwork for future epigenetic studies of I. scapularis in response to B. burgdorferi as well as other pathogens that these ticks transmit.
伯氏疏螺旋体是一种通过蜱传播的螺旋体细菌，因引发莱姆病而广为人知。研究发现，它会在其蜱传播媒介中诱导生理和行为变化，从而提高蜱的适应性及其传播该细菌的能力。这种细菌调节这些变化的机制尚不清楚。表观遗传学在将外部和内部微生物群落环境影响传递给生物体方面起着核心作用，因此我们研究了感染和未感染伯氏疏螺旋体的肩突硬蜱中的DNA甲基化以及一种关键组蛋白修饰酶的表达。通过甲基化DNA免疫沉淀（MeDIP），随后对肩突硬蜱重复序列（ISR）区域进行qPCR，评估了着丝粒周围串联重复序列家族ISR的DNA甲基化情况。发现了ISR序列的DNA甲基化。不同的重复序列具有不同程度的DNA甲基化，然而，这些水平并未受到伯氏疏螺旋体存在与否的显著影响。表观遗传调节因子常染色质组蛋白赖氨酸甲基转移酶2（EHMT2）被认为在调节生物体对感染的应激反应中起关键作用。为了评估感染和未感染伯氏疏螺旋体的蜱中EHMT2的转录情况，进行了实时逆转录PCR。未感染的蜱中EHMT2的表达比感染的蜱低800多倍。这项研究是首批确定一个可能与根据感染状态在蜱中产生表观遗传差异有关的基因的研究之一，为未来关于肩突硬蜱对伯氏疏螺旋体以及这些蜱传播的其他病原体的表观遗传学研究奠定了基础。
