Calhoun Dana M, Woodhams Doug, Howard Cierra, LaFonte Bryan E, Gregory Jacklyn R, Johnson Pieter T J
Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Ramaley N122 CB334, Boulder, CO, 80309, USA.
Department of Biology, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA, 02125, USA.
Ecohealth. 2016 Jun;13(2):383-91. doi: 10.1007/s10393-016-1102-3. Epub 2016 Feb 24.
Antimicrobial peptides (AMPs) contribute to the immune defenses of many vertebrates, including amphibians. As larvae, amphibians are often exposed to the infectious stages of trematode parasites, many of which must penetrate the host's skin, potentially interacting with host AMPs. We tested the effects of the natural AMPs repertoires on both the survival of trematode infectious stages as well as their ability to infect larval amphibians. All five trematode species exhibited decreased survival of cercariae in response to higher concentrations of adult bullfrog AMPs, but no effect when exposed to AMPs from larval bullfrogs. Similarly, the use of norepinephrine to remove AMPs from larval bullfrogs, Pacific chorus frogs, and gray treefrogs had only weak (gray treefrogs) or non-significant (other tested species) effects on infection success by Ribeiroia ondatrae. We nonetheless observed strong differences in parasite infection as a function of both host stage (first- versus second-year bullfrogs) and host species (Pacific chorus frogs versus gray treefrogs) that were apparently unrelated to AMPs. Taken together, our results suggest that AMPs do not play a significant role in defending larval amphibians against trematode cercariae, but that they could be one mechanism helping to prevent infection of post-metamorphic amphibians, particularly for highly aquatic species.
抗菌肽（AMPs）有助于包括两栖动物在内的许多脊椎动物的免疫防御。作为幼体，两栖动物经常接触吸虫寄生虫的感染阶段，其中许多吸虫必须穿透宿主皮肤，这可能与宿主的抗菌肽相互作用。我们测试了天然抗菌肽库对吸虫感染阶段的存活率及其感染两栖动物幼体能力的影响。所有五种吸虫在暴露于较高浓度的成年牛蛙抗菌肽时，尾蚴的存活率均下降，但暴露于幼体牛蛙的抗菌肽时则没有影响。同样，使用去甲肾上腺素去除幼体牛蛙、太平洋树蛙和灰树蛙的抗菌肽，对感染蛙结节吸虫的成功率只有微弱影响（灰树蛙）或无显著影响（其他受试物种）。尽管如此，我们观察到寄生虫感染存在强烈差异，这取决于宿主阶段（第一年与第二年的牛蛙）和宿主物种（太平洋树蛙与灰树蛙），而这显然与抗菌肽无关。综合来看，我们的结果表明，抗菌肽在保护两栖动物幼体免受吸虫尾蚴感染方面并不起重要作用，但它们可能是帮助防止变态后两栖动物感染的一种机制，特别是对于高度水生的物种。
