Data from: Handling stress and sample storage are associated with weaker complement-mediated bactericidal ability in birds but not bats

Variation in immune defense influences infectious disease dynamics within and among species. Understanding how variation in immunity drives pathogen transmission among species is especially important for animals that are reservoir hosts for zoonotic pathogens. Bats in particular have a propensity to host serious viral zoonoses without developing clinical disease themselves. The immunological adaptations that allow bats to host viruses without disease may be related to their adaptations for flight (e.g., in metabolism and mediation of oxidative stress). A number of analyses report greater richness of zoonotic pathogens in bats than in other taxa such as birds (i.e., mostly volant vertebrates) and rodents (i.e., non-volant, small mammals), but immunological comparisons between bats and these other taxa are rare. To examine interspecific differences in bacterial killing ability (BKA), a functional measure of overall constitutive innate immunity, we use a phylogenetic meta-analysis to compare how BKA responds to the acute stress of capture and to storage time of frozen samples across the orders Aves and Chiroptera. After adjusting for host phylogeny, sample size, and total microbe colony-forming units, we find preliminary evidence that constitutive innate immune defense of bats may be more resilient to handling stress and storage time than that of birds. This pattern was also similar when analyzing the proportion of non-negative and positive effect sizes per species using phylogenetic comparative methods. We discuss potential physiological and evolutionary mechanisms by which complement proteins may differ between species orders and suggest future avenues for comparative field studies of immunity between sympatric bats, birds, and rodents in particular.

免疫防御的差异会影响物种内部及物种间的传染病动态。解析免疫差异如何驱动物种间的病原体传播，对于作为人畜共患病原体储存宿主的动物而言尤为关键。其中蝙蝠尤其倾向于携带严重的病毒性人畜共患病原体，自身却不会显现临床病症。蝙蝠能够携带病毒而不致病的免疫适应机制，可能与其飞行相关适应（例如代谢与氧化应激调控）存在关联。多项分析显示，蝙蝠携带的人畜共患病原体丰富度高于鸟类（多为飞行脊椎动物）与啮齿类（非飞行小型哺乳动物）等其他类群，但蝙蝠与这些类群间的免疫学比较研究却较为匮乏。为探究作为整体组成型固有免疫功能指标的细菌杀伤能力（bacterial killing ability, BKA）的种间差异，我们采用系统发育元分析方法，比较鸟纲与翼手目动物的BKA对捕获急性应激以及冷冻样本储存时长的响应模式。在校正宿主系统发育、样本量以及微生物总菌落形成单位后，我们获得初步证据：相较于鸟类，蝙蝠的组成型固有免疫防御对捕获应激与样本储存时长的耐受能力更强。采用系统发育比较方法分析各物种的非负效应量与正效应量占比时，也观察到了相似的模式。我们讨论了不同类群间补体蛋白可能存在差异的潜在生理与进化机制，并特别提出了针对同域分布蝙蝠、鸟类与啮齿类的免疫学比较野外研究的未来方向。