Skin sloughing in susceptible and resistant amphibians regulates infection with a fungal pathogen

The fungal pathogen Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian population declines globally. Given that Bd infection is limited to the skin in post-metamorphic amphibians, routine skin sloughing may regulate infection. Skin sloughing has been shown to reduce the number of cultivatable microbes on amphibian skin, and Bd infection increases skin sloughing rates at high loads. However, it is unclear whether species specific differences in skin sloughing patterns could regulate Bd population growth on the skin, and influence subsequent infection dynamics. We exposed five Australian frog species to Bd, and monitored sloughing rates and infection loads over time. Sloughing reduced Bd load on the ventral skin surface, in all five species, despite wide variation in susceptibility to disease. In the least susceptible species, an increase in sloughing rate occurred at lower infection loads, and sloughing reduced Bd load up to 100%, leading to infection clearance. Convers...

真菌病原体Batrachochytrium dendrobatidis（Bd）已被证实与全球两栖动物种群数量下降有关。鉴于Bd感染在变态后两栖动物（post-metamorphic amphibians）中仅限于皮肤，常规皮肤脱落可能调节感染。已有研究表明，皮肤脱落可减少两栖动物皮肤上可培养微生物（cultivatable microbes）的数量；且当Bd感染负荷较高时，会提高皮肤脱落率。然而，目前尚不清楚皮肤脱落模式的物种特异性差异（species-specific differences）是否能调节皮肤上Bd种群的增长，并影响后续的感染动态（infection dynamics）。我们将五种澳大利亚蛙类暴露于Bd中，并随时间监测其脱落率和感染负荷。尽管五种蛙类的疾病易感性（susceptibility to disease）存在显著差异，但皮肤脱落均降低了其腹侧皮肤表面（ventral skin surface）的Bd负荷。在疾病易感性最低的物种中，较低的感染负荷即可引发脱落率上升，且皮肤脱落可将Bd负荷降低100%，从而实现感染清除（infection clearance）。