Data from: Landscape features and helminth co-infection shape bank vole immunoheterogeneity, with consequences for Puumala virus epidemiology

Heterogeneity in environmental conditions helps to maintain genetic and phenotypic diversity in ecosystems. As such, it may explain why the capacity of animals to mount immune responses is highly variable. The quality of habitat patches, in terms of resources, parasitism, predation and habitat fragmentation may, for example, trigger trade-offs ultimately affecting the investment of individuals in various immunological pathways. We described spatial immunoheterogeneity in bank vole populations with respect to landscape features and co-infection. We focused on the consequences of this heterogeneity for the risk of Puumala hantavirus (PUUV) infection. We assessed the expression of the Tnf-α and Mx2 genes and demonstrated a negative correlation between PUUV load and the expression of these immune genes in bank voles. Habitat heterogeneity was partly associated with differences in the expression of these genes. Levels of Mx2 were lower in large forests than in fragmented forests, possibly due to differences in parasite communities. We previously highlighted the positive association between infection with Heligmosomum mixtum and infection with PUUV. We found that Tnf-α was more strongly expressed in voles infected with PUUV than in uninfected voles or in voles co-infected with the nematode H. mixtum and PUUV. H. mixtum may limit the capacity of the vole to develop proinflammatory responses. This effect may increase the risk of PUUV infection and replication in host cells. Overall, our results suggest that close interactions between landscape features, co-infection and immune gene expression may shape PUUV epidemiology.

环境异质性有助于维持生态系统内的遗传与表型多样性。据此，这或可解释为何动物的免疫应答能力存在显著差异。例如，栖息地斑块的质量——从资源可获得性、寄生压力、捕食风险与栖息地破碎化等维度衡量——可能引发权衡效应，最终影响个体在各类免疫通路中的资源投入。本研究针对景观特征与共感染情况，分析了棕背䶄种群的空间免疫异质性，并聚焦于该异质性对普马拉汉坦病毒（Puumala hantavirus，PUUV）感染风险的影响。本研究检测了肿瘤坏死因子α（Tnf-α）与Mx2基因的表达水平，证实棕背䶄体内的PUUV载量与这两类免疫基因的表达呈负相关关系。栖息地异质性与上述基因的表达差异存在部分关联。大型森林中的Mx2基因表达水平低于破碎化森林，这一现象或与寄生虫群落结构差异相关。此前本团队已证实，混合卷尾线虫（Heligmosomum mixtum）感染与PUUV感染存在正相关关联。本研究发现，感染PUUV的棕背䶄体内Tnf-α的表达水平高于未感染个体，同时也高于同时感染混合卷尾线虫与PUUV的个体。混合卷尾线虫可能会抑制棕背䶄的促炎应答能力，该效应或会提升PUUV在宿主细胞内感染与复制的风险。综合来看，本研究结果表明，景观特征、共感染与免疫基因表达三者间的紧密互作，或可塑造普马拉汉坦病毒的流行病学特征。