School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
Ecohealth. 2009 Sep;6(3):438-48. doi: 10.1007/s10393-010-0279-0. Epub 2010 Feb 9.
Infectious diseases are a growing threat to biodiversity, in many cases because of synergistic effects with habitat loss, environmental contamination, and climate change. Emergence of pathogens as new threats to host populations can also arise when novel combinations of hosts and pathogens are unintentionally brought together, for example, via commercial trade or wildlife relocations and reintroductions. Chytrid fungus (Batrachochytrium dendrobatidis) and amphibian ranaviruses (family Iridoviridae) are pathogens implicated in global amphibian declines. The emergence of disease associated with these pathogens appears to be at least partly related to recent translocations over large geographic distances. We experimentally examined the outcomes of novel combinations of host populations and pathogen strains using the amphibian ranavirus Ambystoma tigrinum virus (ATV) and barred tiger salamanders (Ambystoma mavortium, formerly considered part of the Ambystoma tigrinum complex). One salamander population was highly resistant to lethal infections by all ATV strains, including its own strain, and mortality rates differed among ATV strains according to salamander population. Mortality rates in novel pairings of salamander population and ATV strain were not predictable based on knowledge of mortality rates when salamander populations were exposed to their own ATV strain. The underlying cause(s) for the differences in mortality rates are unknown, but local selection pressures on salamanders, viruses, or both, across the range of this widespread host-pathogen system are a plausible hypothesis. Our study highlights the need to minimize translocations of amphibian ranaviruses, even among conspecifc host populations, and the importance of considering intraspecific variation in endeavors to manage wildlife diseases.
传染病是生物多样性面临的一个日益严重的威胁，在许多情况下，这是由于与栖息地丧失、环境污染和气候变化的协同作用造成的。当宿主和病原体的新组合在商业贸易或野生动物迁移和再引入等情况下无意中聚集在一起时，病原体也可能作为宿主种群的新威胁出现。蛙壶菌（Batrachochytrium dendrobatidis）和两栖动物虹彩病毒（虹彩病毒科）是与全球两栖动物减少有关的病原体。与这些病原体相关的疾病的出现似乎至少部分与最近在大地理距离上的迁移有关。我们使用两栖动物虹彩病毒 Ambystoma tigrinum 病毒（ATV）和条纹虎蝾螈（Ambystoma mavortium，以前被认为是 Ambystoma tigrinum 复合体的一部分），实验性地研究了宿主种群和病原体菌株的新组合的结果。一个蝾螈种群对所有 ATV 菌株的致命感染具有高度抗性，包括其自身的菌株，并且根据蝾螈种群的不同，ATV 菌株的死亡率也不同。根据蝾螈种群暴露于其自身 ATV 菌株时的死亡率，无法预测新的蝾螈种群和 ATV 菌株组合的死亡率。死亡率差异的根本原因尚不清楚，但在这个广泛的宿主-病原体系统的范围内，对蝾螈、病毒或两者的局部选择压力是一个合理的假设。我们的研究强调了需要最小化两栖动物虹彩病毒的迁移，即使是在同种宿主种群之间，并且在管理野生动物疾病的努力中考虑种内变异的重要性。
