Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315, Berlin, Germany; Institute of Biology, Freie Universität Berlin, Takustr. 6, 14195, Berlin, Germany.
Institut des Sciences de L'Evolution, University of Montpellier, CNRS, EPHE, IRD, Montpellier, 34095, Montpellier, France.
Dev Comp Immunol. 2021 Jun;119:104017. doi: 10.1016/j.dci.2021.104017. Epub 2021 Jan 18.
Pseudogymnoascus destructans (Pd), the causative agent of white-nose syndrome in North America, has decimated bat populations within a decade. The fungus impacts bats during hibernation when physiological functions, including immune responses, are down-regulated. Studies have shown that Pd is native to Europe, where it is not associated with mass mortalities. Moreover, genomic and proteomic studies indicated that European bats may have evolved an effective immune defence, which is lacking in North American bats. However, it is still unclear which defence strategy enables European bats to cope with the pathogen. Here, we analyzed selected physiological and immunological parameters in torpid, Pd infected European greater mouse-eared bats (Myotis myotis) showing three different levels of infection (asymptomatic, mild and severe symptoms). From a subset of the studied bats we tracked skin temperatures during one month of hibernation. Contrasting North American bats, arousal patterns remained unaffected by Pd infections in M. myotis. In general, heavier M. myotis aroused more often from hibernation and showed less severe disease symptoms than lean individuals; most likely because heavy bats were capable of reducing the Pd load more effectively than lean individuals. In the blood of severely infected bats, we found higher gene expression levels of an inflammatory cytokine (IL-1β), but lower levels of an acute phase protein (haptoglobin), reactive oxygen metabolites (ROMs) and plasma non-enzymatic antioxidant capacity (OXY) compared to conspecifics with lower levels of infection. We conclude that M. myotis, and possibly also other European bat species, tolerate Pd infections during torpor by using selected acute phase response parameters at baseline levels, yet without arousing from torpor and without synthesizing additional immune molecules.
假丝酵母菌（Pd）是北美的白鼻综合征的病原体，在十年内使蝙蝠数量锐减。当生理功能（包括免疫反应）下调时，真菌会在蝙蝠冬眠时对其产生影响。研究表明，Pd 原产于欧洲，在那里它与大规模死亡无关。此外，基因组和蛋白质组学研究表明，欧洲蝙蝠可能已经进化出有效的免疫防御机制，而北美蝙蝠则缺乏这种机制。然而，目前尚不清楚哪种防御策略使欧洲蝙蝠能够应对这种病原体。在这里，我们分析了在感染 Pd 的欧洲大耳蝠（Myotis myotis）中处于三种不同感染水平（无症状、轻度和重度症状）的休眠期的选定生理和免疫学参数。我们从研究的蝙蝠中选取了一部分，在一个月的冬眠期间跟踪它们的皮肤温度。与北美的蝙蝠不同，Pd 感染不会影响 M. myotis 的唤醒模式。一般来说，体重较重的蝙蝠从冬眠中唤醒的次数更多，且疾病症状比瘦的个体更轻；这很可能是因为体重较重的蝙蝠能够比瘦的个体更有效地减少 Pd 负荷。在重度感染的蝙蝠血液中，我们发现炎症细胞因子（IL-1β）的基因表达水平较高，但急性相蛋白（触珠蛋白）、活性氧代谢物（ROMs）和血浆非酶抗氧化能力（OXY）水平较低，与感染水平较低的同物种蝙蝠相比。我们得出结论，M. myotis 可能还有其他欧洲蝙蝠物种，通过在基线水平上使用选定的急性期反应参数来耐受 Pd 感染，而不会从休眠中唤醒，也不会合成额外的免疫分子。
