Department of Biology, University of South Florida, Tampa, FL 33620, USA.
Int J Parasitol. 2009 Jan;39(2):231-41. doi: 10.1016/j.ijpara.2008.06.011. Epub 2008 Jul 26.
Acquired immune memory in vertebrates influences transmission and persistence of infections, with consequences for parasite dynamics at both the individual and population levels. The potential impact of acquired immunity is of particular interest for salamanders, whose acquired immune systems are thought to be less effective than those of frogs and other tetrapods. One way to examine the importance of acquired immunity to parasite dynamics at the population level is by examining the relationship between host age and parasite infection intensity. Acquired immunity reduces infection rates in older animals, causing decreased parasite intensity in older age classes and leading to curvilinear age-intensity relationships for persistent parasites and convex age-intensity relationships for transient parasites. We used age-intensity relationships to look for the signature of acquired immunity for 12 parasite taxa of red-spotted newts (Notophthalmus viridescens), using data from a 2-year parasitological survey of six newt populations. We estimated ages from snout-vent length (SVL) based on the relationship between SVL and skeletochronologically-derived ages in a subset of newts. We found evidence of acquired immunity to two parasite taxa, bacterial pathogens and the protist Amphibiocystidium viridescens, whose convex age-intensity relationships could not be easily explained by alternative mechanisms. Our results suggest that the acquired immune response of newts is sufficient to influence the dynamics of at least some parasites.
脊椎动物获得性免疫记忆影响感染的传播和持续，从而对个体和种群水平上寄生虫的动态产生影响。获得性免疫的潜在影响对于蝾螈尤为重要，因为人们认为它们的获得性免疫系统不如青蛙和其他四足动物有效。一种检验获得性免疫对种群水平寄生虫动态重要性的方法是检查宿主年龄与寄生虫感染强度之间的关系。获得性免疫会降低老年动物的感染率，导致老年个体寄生虫强度降低，从而导致持续性寄生虫呈曲线形年龄-强度关系，而短暂性寄生虫呈凸形年龄-强度关系。我们使用年龄-强度关系来寻找 12 种红斑蝾螈寄生虫（Notophthalmus viridescens）的获得性免疫特征，这些寄生虫的数据来自对六个红斑蝾螈种群进行的为期两年的寄生虫学调查。我们根据 SVL 和骨骼年代学衍生年龄之间的关系，从 SVL 估计年龄，这是在一小部分蝾螈中得出的。我们发现了两种寄生虫（细菌病原体和原生动物 Amphibiocystidium viridescens）具有获得性免疫的证据，它们的凸形年龄-强度关系不能用其他机制来简单解释。我们的研究结果表明，蝾螈的获得性免疫反应足以影响至少一些寄生虫的动态。
