Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
Proc Biol Sci. 2018 Nov 7;285(1890):20182075. doi: 10.1098/rspb.2018.2075.
Parasite epidemics can depend on priority effects, and parasite priority effects can result from the host immune response to prior infection. Yet we lack experimental evidence that such immune-mediated priority effects influence epidemics. To address this research gap, we manipulated key host immune hormones, then measured the consequences for within-host parasite interactions, and ultimately parasite epidemics in the field. Specifically, we applied plant immune-signalling hormones to sentinel plants, embedded into a wild host population, and tracked foliar infections caused by two common fungal parasites. Within-host individuals, priority effects were altered by the immune-signalling hormone, salicylic acid (SA). Scaling up from within-host interactions, hosts treated with SA experienced a lower prevalence of a less aggressive parasite, increased burden of infection by a more aggressive parasite, and experienced fewer co-infections. Together, these results indicate that by altering within-host priority effects, host immune hormones can drive parasite epidemics. This study therefore experimentally links host immune hormones to within-host priority effects and parasite epidemics, advancing a more mechanistic understanding of how interactions among parasites alter their epidemics.
寄生虫流行可能取决于优先效应，而寄生虫的优先效应可能源于宿主对先前感染的免疫反应。然而，我们缺乏实验证据表明这种免疫介导的优先效应会影响流行。为了解决这一研究空白，我们操纵了关键的宿主免疫激素，然后测量了它们对宿主内寄生虫相互作用以及最终在野外寄生虫流行的影响。具体来说，我们将植物免疫信号激素应用于哨兵植物，将其嵌入到野生宿主群体中，并追踪由两种常见真菌寄生虫引起的叶片感染。在宿主内个体中，免疫信号激素水杨酸（SA）改变了优先效应。从宿主内相互作用扩展来看，用 SA 处理的宿主经历了一种侵袭性较弱的寄生虫的流行率降低，侵袭性较强的寄生虫的感染负担增加，并且共同感染的情况减少。总之，这些结果表明，通过改变宿主内的优先效应，宿主免疫激素可以驱动寄生虫流行。因此，本研究通过实验将宿主免疫激素与宿主内优先效应和寄生虫流行联系起来，进一步了解寄生虫之间的相互作用如何改变它们的流行。
