Data from: Frequent and seasonally variable sublethal anthrax infections are accompanied by short-lived immunity in an endemic system

1. Few studies have examined host-pathogen interactions in wildlife from an immunological perspective, particularly in the context of seasonal and longitudinal dynamics. In addition, though most ecological immunology studies employ serological antibody assays, endpoint titer determination is usually based on subjective criteria and needs to be made more objective. 2. Despite the fact that anthrax is an ancient and emerging zoonotic infectious disease found worldwide, its natural ecology is not well understood. In particular, little is known about the adaptive immune responses of wild herbivore hosts against Bacillus anthracis. 3. Working in the natural anthrax system of Etosha National Park, Namibia, we collected 154 serum samples from plains zebra (Equus quagga), 21 from springbok (Antidorcas marsupialis), and 45 from African elephants (Loxodonta africana) over 2-3 years, resampling individuals when possible for seasonal and longitudinal comparisons. We used enzyme-linked immunosorbent assays to measure anti-anthrax antibody titers and developed three increasingly conservative models to determine endpoint titers with more rigorous, objective mensuration. 4. Between 52-87% of zebra, 0-15% of springbok, and 3-52% of elephants had measurable anti-anthrax antibody titers, depending on the model used. While the ability of elephants and springbok to mount anti-anthrax adaptive immune responses is still equivocal, our results indicate that zebra in ENP often survive sublethal anthrax infections, encounter most B. anthracis in the wet season, and can partially booster their immunity to B. anthracis. 5. Thus, rather than being solely a lethal disease, anthrax often occurs as a sublethal infection in some susceptible hosts. Though we found that adaptive immunity to anthrax wanes rapidly, subsequent and frequent sublethal B. anthracis infections cause maturation of anti-anthrax immunity. By triggering host immune responses, these common sublethal infections may act as immunomodulators and affect population dynamics through indirect immunological and co-infection effects. 6. In addition, with our three endpoint titer models, we introduce more mensuration rigor into serological antibody assays, even under the often-restrictive conditions that come with adapting laboratory immunology methods to wild systems. With these methods we identified significantly more zebras responding immunologically to anthrax than have previous studies using less comprehensive titer analyses.1. 目前鲜有研究从免疫学视角探究野生动物的宿主-病原体（host-pathogen）互作关系，尤其是在季节动态与纵向动态的背景下。此外，尽管多数生态免疫学研究采用血清学抗体检测（serological antibody assays）技术，但终点效价（endpoint titer）的测定通常基于主观标准，亟需进一步实现客观化。2. 尽管炭疽（anthrax）是一种在全球范围内分布的古老且新发的人畜共患传染病，但其天然生态学特征仍未得到充分阐明。尤为关键的是，目前对于野生草食动物宿主针对炭疽芽孢杆菌（Bacillus anthracis）的适应性免疫应答机制仍知之甚少。3. 本研究在纳米比亚埃托沙国家公园的天然炭疽流行系统中开展，于2-3年的周期内采集了平原斑马（Equus quagga）的血清样本154份、跳羚（Antidorcas marsupialis）21份以及非洲象（Loxodonta africana）45份；在条件允许的情况下，对个体进行重采样以开展季节动态与纵向对比分析。本研究采用酶联免疫吸附试验（enzyme-linked immunosorbent assays）检测抗炭疽抗体效价，并构建了三种逐渐严格的模型，以通过更严谨、客观的测定方法确定终点效价。4. 根据所采用的模型不同，52%~87%的斑马、0%~15%的跳羚以及3%~52%的非洲象可检测到抗炭疽抗体效价。尽管目前对于大象和跳羚能否产生抗炭疽适应性免疫应答仍不明确，但本研究结果显示，埃托沙国家公园内的斑马通常可耐受亚致死剂量的炭疽感染，且多数炭疽芽孢杆菌暴露发生于湿季，斑马可部分增强其针对该菌的免疫力。5. 由此可见，炭疽并非仅表现为致死性疾病，在部分易感宿主中，其常以亚致死感染的形式存在。尽管本研究发现抗炭疽适应性免疫会快速衰退，但后续频繁发生的亚致死性炭疽芽孢杆菌感染可促进抗炭疽免疫力的成熟。这类常见的亚致死感染可通过触发宿主免疫应答发挥免疫调节作用，并通过间接的免疫学效应与共感染效应影响种群动态。6. 此外，依托我们构建的三种终点效价测定模型，本研究为血清学抗体检测技术引入了更严格的测定规范，即便在将实验室免疫学方法适配至野外研究体系时所面临的诸多限制条件下亦是如此。相较于此前采用更为简化的效价分析方法的研究，本研究通过上述方法鉴定出了更多对炭疽产生免疫应答的斑马个体。