Piovia-Scott Jonah, Pope Karen, Worth S Joy, Rosenblum Erica Bree, Poorten Thomas, Refsnider Jeanine, Rollins-Smith Louise A, Reinert Laura K, Wells Heather L, Rejmanek Dan, Lawler Sharon, Foley Janet
Department of Biology, University of California, Riverside, CA, USA.
Pacific Southwest Research Station, United States Forest Service, Arcata, CA, USA.
ISME J. 2015 Jul;9(7):1570-8. doi: 10.1038/ismej.2014.241. Epub 2014 Dec 16.
The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused declines and extinctions in amphibians worldwide, and there is increasing evidence that some strains of this pathogen are more virulent than others. While a number of putative virulence factors have been identified, few studies link these factors to specific epizootic events. We documented a dramatic decline in juvenile frogs in a Bd-infected population of Cascades frogs (Rana cascadae) in the mountains of northern California and used a laboratory experiment to show that Bd isolated in the midst of this decline induced higher mortality than Bd isolated from a more stable population of the same species of frog. This highly virulent Bd isolate was more toxic to immune cells and attained higher density in liquid culture than comparable isolates. Genomic analyses revealed that this isolate is nested within the global panzootic lineage and exhibited unusual genomic patterns, including increased copy numbers of many chromosomal segments. This study integrates data from multiple sources to suggest specific phenotypic and genomic characteristics of the pathogen that may be linked to disease-related declines.
真菌病原体蛙壶菌（Batrachochytrium dendrobatidis，简称Bd）已导致全球两栖动物数量减少和灭绝，而且越来越多的证据表明，该病原体的某些菌株比其他菌株更具毒性。虽然已经确定了一些假定的毒力因子，但很少有研究将这些因子与特定的动物流行病事件联系起来。我们记录了加利福尼亚州北部山区感染Bd的喀斯喀特蛙（Rana cascadae）种群中幼蛙数量的急剧下降，并通过实验室实验表明，在此次数量下降期间分离出的Bd菌株比从同一物种较稳定种群中分离出的Bd菌株诱导更高的死亡率。这种高毒力的Bd分离株对免疫细胞毒性更大，在液体培养中比同类分离株达到更高的密度。基因组分析表明，该分离株嵌套在全球泛动物源谱系中，并表现出不寻常的基因组模式，包括许多染色体片段的拷贝数增加。这项研究整合了来自多个来源的数据，以表明病原体的特定表型和基因组特征可能与疾病相关的数量下降有关。
