PDF(Pubmed)
Abstract：
The trade-off between within-host infection rate and transmission to new hosts is predicted to constrain pathogen evolution, and to maintain polymorphism in pathogen populations. Pathogen life-history stages and their correlations that underpin infection development may change under coinfection with other parasites as they compete for the same limited host resources. Cross-kingdom interactions are common among pathogens in both natural and cultivated systems, yet their impacts on disease ecology and evolution are rarely studied. The host plant Plantago lanceolata is naturally infected by both Phomopsis subordinaria, a seed killing fungus, as well as Plantago lanceolata latent virus (PlLV) in the Åland Islands, SW Finland. We performed an inoculation assay to test whether coinfection with PlLV affects performance of two P. subordinaria strains, and the correlation between within-host infection rate and transmission potential. The strains differed in the measured life-history traits and their correlations. Moreover, we found that under virus coinfection, within-host infection rate of P. subordinaria was smaller but transmission potential was higher compared to strains under single infection. The negative correlation between within-host infection rate and transmission potential detected under single infection became positive under coinfection with PlLV. To understand whether within-host and between-host dynamics are correlated in wild populations, we surveyed 260 natural populations of P. lanceolata for P. subordinaria infection occurrence. When infections were found, we estimated between-hosts dynamics by determining pathogen population size as the proportion of infected individuals, and within-host dynamics by counting the proportion of infected flower stalks in 10 infected plants. In wild populations, the proportion of infected flower stalks was positively associated with pathogen population size. Jointly, our results suggest that the trade-off between within-host infection load and transmission may be strain specific, and that the pathogen life-history that underpin epidemics may change depending on the diversity of infection, generating variation in disease dynamics.
摘要：
预计宿主内感染率和向新宿主的传播之间的权衡将限制病原体的进化，并保持病原体种群的多态性。病原体生活史阶段及其与感染发展的相关性可能在与其他寄生虫共同感染时发生变化，因为它们竞争相同的有限宿主资源。跨王国的相互作用在自然和栽培系统中的病原体中很常见，然而，它们对疾病生态学和进化的影响却很少被研究。寄主植物车前草自然感染了两个副触毛，一种杀死种子的真菌，以及奥兰群岛的车前草潜伏病毒（PlLV），芬兰西南部。我们进行了接种试验，以测试是否与PlLV共同感染会影响两种P.subraria菌株的性能，以及宿主内感染率与传播潜力之间的相关性。菌株在测得的生活史特征及其相关性上有所不同。此外，我们发现在病毒共感染下，与单一感染下的菌株相比，次级疟原虫的宿主内感染率较小，但传播潜力较高。与PlLV共感染时，单次感染下检测到的宿主内感染率与传播电位之间呈负相关。要了解野生种群中宿主内和宿主间的动态是否相关，我们调查了260个自然种群的杉木。当发现感染时，我们通过确定病原体种群大小作为受感染个体的比例来估计宿主间动态，和寄主内动态，通过计算10株感染植物中感染花茎的比例。在野生种群中，感染花茎的比例与病原体种群大小呈正相关。联合,我们的结果表明，宿主内感染负荷和传播之间的权衡可能是菌株特异性的，并且支持流行病的病原体生活史可能会根据感染的多样性而改变，在疾病动力学中产生变化。
