Mixed Infections and the Evolution of Virulence: Effects of Resource Competition, Parasite Plasticity, and Impaired Host Immunity
Mixed Infections and the Evolution of Virulence: Effects of Resource Competition, Parasite Plasticity, and Impaired Host Immunity
复制标题
DOI：
10.1086/651587
复制
发表时间：
2010-05-01
影响因子：
2.9
通讯作者：
de Roode, Jacobus C.
中科院分区：
文献类型：
--
作者：
Choisy, Marc;de Roode, Jacobus C.
混合基因型寄生虫感染在自然界中很常见。理论研究分析了此类感染在进化过程中的影响，并预测由于剧毒寄生虫的竞争优势，毒力会增加。相比之下，实验研究比较了一代内混合和单一感染的总体毒力。尽管这些代内比较与现有理论的相关性有限，但它们表明宿主寄生虫内的相互作用并不限于理论所设想的资源竞争。相反，混合感染可能会导致生长速度的表型变化或免疫清除受损。开发和使用具有恢复功能的两种寄生虫流行病学模型，我们证实宿主内部对资源的竞争会选择更高的毒力。然而，寄生虫表型可塑性和宿主免疫力受损可以选择较低的毒力。因为后两种机制会被实验者检测为病理学的增加，所以我们的结果警告不要在单代实验的基础上对毒力进化进行推断。
Mixed-genotype parasite infections are common in nature. Theoretical studies analyze the effects of such infections over evolutionary time and predict an increase in virulence due to the competitive advantage of virulent parasites. In contrast, experimental studies compare the overall virulence of mixed and single infections within one generation. Although these within-generation comparisons have limited relevance to existing theory, they demonstrate that within-host parasite interactions are not restricted to competition for resources, as envisaged by theory. Instead, mixed infections may result in phenotypic changes in growth rate or impaired immune clearance. Developing and using a two-parasite epidemiological model with recovery, we confirm that within-host competition for resources selects for higher virulence. However, parasite phenotypic plasticity and impaired host immunity can select for lower virulence. Because these latter two mechanisms would be detected by experimentalists as an increase in pathology, our results warn against the temptation to draw inferences on virulence evolution on the basis of single-generation experiments.