Competitive coexistence of two Pneumocystis species.
Competitive coexistence of two Pneumocystis species.
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两种肺孢子虫物种竞争性共存。
DOI：
10.1016/j.meegid.2005.03.004
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Cushion,MelanieT
中科院分区：
文献类型：
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作者：
Icenhour,CrystalR;Arnold,Jonathan;Medvedovic,Mario;Cushion,MelanieT
肺囊虫是哺乳动物肺部的真菌病原体，可在免疫功能低下的宿主中引起致命性肺炎。在一些哺乳动物中，已发现遗传上不同的肺囊虫种群的共感染，但其相互作用的性质及其意义尚不清楚。两种感染大鼠的肺囊虫，卡氏肺囊虫和韦克菲尔德肺囊虫，在6年的时间里被研究，代表了大约700代肺囊虫。在Lotka-Volterra竞争模型框架内分析了各物种的种群密度，结果表明两个物种处于竞争状态，并预测了一个物种的竞争排斥。然而，在460个重复群体中观察到稳定的共存。选择可能减轻灭绝的外部因素进行了评估。logistic回归分析显示，较高的相对湿度和较高的肺负荷与单独由卡氏假单胞菌组成的感染有关，而较低的温度和增加的鼠普查与韦克菲尔德假单胞菌的存在有关。对大鼠肺组织的PCR和免疫荧光分析显示，这两个物种存在于同一个肺泡内，排除了栖息地异质性作为共存机制的可能性。这些数据表明，P. carinii和P. wakefieldiae处于竞争共存状态，这在一定程度上受外部因素的影响。据我们所知，这是第一份利用生态模型评估哺乳动物宿主内病原真菌物种相互作用的报告。
Pneumocystis are fungal pathogens of mammalian lungs that can cause lethal pneumonia in immunocompromised hosts. In some mammals, coinfections of genetically distinct Pneumocystis populations have been identified, but the nature of their interaction and its significance are unknown. Two species that infect rats, Pneumocystis carinii and Pneumocystis wakefieldiae, were studied over a 6-year period, representing approximately 700 generations of Pneumocystis. Population densities of each species were analyzed within the framework of the Lotka–Volterra competition model, which revealed the two species were in competition and predicted competitive exclusion of one species. However, stable coexistence was observed in 460 replicate populations. Selected extrinsic factors that might mitigate the extinction were evaluated. Logistic-regression analyses showed that higher relative humidity and higher organism lung burdens were associated with infections comprised of P. carinii alone, while lower temperatures and an increased rat census were associated with the presence of P. wakefieldiae. PCR and immunofluorescent analysis of rat lung tissue showed that both species were present within the same alveoli, excluding habitat heterogeneity as a mechanism of coexistence. These data suggest that P. carinii and P. wakefieldiae were in competitive coexistence, which was influenced in part by extrinsic factors. To our knowledge, this is the first report to evaluate interactions of pathogenic fungal species within a mammalian host using ecological models.