Department of Biology, Center for Ecology and Conservation Biology, Boston University, Boston, Massachusetts, United States of America.
PLoS One. 2011;6(11):e27430. doi: 10.1371/journal.pone.0027430. Epub 2011 Nov 30.
White-nose syndrome (WNS) is the most devastating condition ever reported for hibernating bats, causing widespread mortality in the northeastern United States. The syndrome is characterized by cutaneous lesions caused by a recently identified psychrophilic and keratinophylic fungus (Geomyces destructans), depleted fat reserves, atypical behavior, and damage to wings; however, the proximate cause of mortality is still uncertain. To assess relative levels of immunocompetence in bats hibernating in WNS-affected sites compared with levels in unaffected bats, we describe blood plasma complement protein activity in hibernating little brown myotis (Myotis lucifugus) based on microbicidal competence assays using Escherichia coli, Staphylococcus aureus and Candida albicans. Blood plasma from bats collected during mid-hibernation at WNS-affected sites had higher bactericidal ability against E. coli and S. aureus, but lower fungicidal ability against C. albicans when compared with blood plasma from bats collected at unaffected sites. Within affected sites during mid-hibernation, we observed no difference in microbicidal ability between bats displaying obvious fungal infections compared to those without. Bactericidal ability against E. coli decreased significantly as hibernation progressed in bats collected from an affected site. Bactericidal ability against E. coli and fungicidal ability against C. albicans were positively correlated with body mass index (BMI) during late hibernation. We also compared complement activity against the three microbes within individuals and found that the ability of blood plasma from hibernating M. lucifugus to lyse microbial cells differed as follows: E. coli>S. aureus>C. albicans. Overall, bats affected by WNS experience both relatively elevated and reduced innate immune responses depending on the microbe tested, although the cause of observed immunological changes remains unknown. Additionally, considerable trade-offs may exist between energy conservation and immunological responses. Relationships between immune activity and torpor, including associated energy expenditure, are likely critical components in the development of WNS.
白色鼻子综合征（WNS）是迄今为止报道的冬眠蝙蝠最具破坏性的疾病，导致美国东北部蝙蝠大量死亡。该综合征的特征是由最近发现的嗜冷和角蛋白真菌（Geomyces destructans）引起的皮肤损伤、脂肪储备减少、异常行为和翅膀损伤；然而，死亡的直接原因仍不确定。为了评估在受 WNS 影响的地点冬眠的蝙蝠与未受影响的蝙蝠相比的相对免疫能力水平，我们根据使用大肠杆菌、金黄色葡萄球菌和白色念珠菌的杀菌能力测定来描述冬眠小褐蝙蝠（Myotis lucifugus）的血浆补体蛋白活性。与在未受影响的地点收集的蝙蝠的血浆相比，在受 WNS 影响的地点在冬眠中期收集的蝙蝠的血浆对大肠杆菌和金黄色葡萄球菌具有更高的杀菌能力，但对白色念珠菌的杀菌能力较低。在冬眠中期，在受影响的地点，我们观察到表现出明显真菌感染的蝙蝠与没有真菌感染的蝙蝠之间的杀菌能力没有差异。在受影响的地点从蝙蝠收集的 E. coli 的杀菌能力随着冬眠的进展而显著下降。在晚期冬眠期间，E. coli 的杀菌能力和对 C. albicans 的杀菌能力与体重指数（BMI）呈正相关。我们还比较了个体内针对这三种微生物的补体活性，发现冬眠 M. lucifugus 血浆裂解微生物细胞的能力如下：E. coli>S. aureus>C. albicans。总体而言，受 WNS 影响的蝙蝠根据测试的微生物表现出相对升高和降低的固有免疫反应，尽管观察到的免疫变化的原因仍然未知。此外，在能量保存和免疫反应之间可能存在相当大的权衡。免疫活性与蛰伏之间的关系，包括相关的能量消耗，可能是 WNS 发展的关键组成部分。
