Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada.
Department of Veterinary Medicine, University of Alaska Fairbanks, Fairbanks, AK, United States of America.
PLoS One. 2021 Oct 29;16(10):e0258975. doi: 10.1371/journal.pone.0258975. eCollection 2021.
Patterns of local adaptation can emerge in response to the selective pressures diseases exert on host populations as reflected in increased frequencies of respective, advantageous genotypes. Elucidating patterns of local adaptation enhance our understanding of mechanisms of disease spread and the capacity for species to adapt in context of rapidly changing environments such as the Arctic. Arctic rabies is a lethal disease that largely persists in northern climates and overlaps with the distribution of its natural host, arctic fox. Arctic fox populations display little neutral genetic structure across their North American range, whereas phylogenetically unique arctic rabies variants are restricted in their geographic distributions. It remains unknown if arctic rabies variants impose differential selection upon host populations, nor what role different rabies variants play in the maintenance and spread of this disease. Using a targeted, genotyping-by-sequencing assay, we assessed correlations of arctic fox immunogenetic variation with arctic rabies variants to gain further insight into the epidemiology of this disease. Corroborating past research, we found no neutral genetic structure between sampled regions, but did find moderate immunogenetic structuring between foxes predominated by different arctic rabies variants. FST outliers associated with host immunogenetic structure included SNPs within interleukin and Toll-like receptor coding regions (IL12B, IL5, TLR3 and NFKB1); genes known to mediate host responses to rabies. While these data do not necessarily reflect causation, nor a direct link to arctic rabies, the contrasting genetic structure of immunologically associated candidate genes with neutral loci is suggestive of differential selection and patterns of local adaptation in this system. These data are somewhat unexpected given the long-lived nature and dispersal capacities of arctic fox; traits expected to undermine local adaptation. Overall, these data contribute to our understanding of the co-evolutionary relationships between arctic rabies and their primary host and provide data relevant to the management of this disease.
地方适应模式可以因疾病对宿主种群施加的选择压力而出现，这反映在各自有利基因型的频率增加上。阐明地方适应模式可以增强我们对疾病传播机制以及物种在快速变化的环境（如北极）中适应能力的理解。北极狂犬病是一种致命疾病，主要在北方气候中存在，并与北极狐等自然宿主的分布重叠。北极狐在其北美的分布范围内几乎没有中性遗传结构，而在地理分布上受到限制的是具有独特进化历史的北极狂犬病变体。目前尚不清楚北极狂犬病变体是否对宿主种群施加了不同的选择压力，也不知道不同的狂犬病变体在维持和传播这种疾病方面发挥了什么作用。本研究使用靶向、测序分型的基因分型方法，评估了北极狐免疫遗传变异与北极狂犬病变体的相关性，以进一步了解这种疾病的流行病学。与过去的研究结果一致，我们在采样区域之间没有发现中性遗传结构，但在不同北极狂犬病变体占主导地位的狐狸之间发现了中度的免疫遗传结构。与宿主免疫遗传结构相关的 FST 异常值包括白细胞介素和 Toll 样受体编码区域（IL12B、IL5、TLR3 和 NFKB1）内的 SNP；这些基因已知介导宿主对狂犬病的反应。虽然这些数据不一定反映因果关系，也与北极狂犬病没有直接联系，但与中性基因座相关的免疫相关候选基因的遗传结构的对比表明，在该系统中存在不同的选择和地方适应模式。鉴于北极狐的寿命长和扩散能力强；这些特征预计会破坏地方适应。总的来说，这些数据有助于我们了解北极狂犬病与其主要宿主之间的协同进化关系，并为这种疾病的管理提供相关数据。
