Infectious Dose Affects the Outcome of the Within-Host Competition between Parasites
Infectious Dose Affects the Outcome of the Within-Host Competition between Parasites
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DOI：
10.1086/598490
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发表时间：
2009-06-01
影响因子：
2.9
通讯作者：
Koella, Jacob C.
中科院分区：
文献类型：
--
作者：
Fellous, Simon;Koella, Jacob C.
寄生虫在个体宿主内竞争成功的生态学和流行病学过程尚不清楚。我们研究了一个想法：增加一种寄生虫的感染剂量可能会减少其竞争对手的成功。我们饲养未受感染的埃及伊蚊幼虫，并将其暴露于两种浓度的微孢子虫Vavraia cultured和原生动物Ascogregarina cultured。Vavraia产生感染性孢子的速率取决于其剂量及其竞争对手：当Vavraia的剂量高时，只有较高剂量的Ascogregarina减缓了孢子的产生，但当剂量低时，任何剂量的Ascogregarina都是如此。当其竞争对手的剂量很高，并且蚊子在食物很少的情况下饲养时，Ascogregarina产生卵囊的可能性最小。这是由于Vavraia引起的蚊子的成虫前死亡。我们的研究结果表明，增加寄生虫的剂量可以增加其对共感染寄生虫的有害影响。由于剂量随着寄生虫的流行而增加，这种剂量效应可能导致流行病学反馈，最终消除其中一种寄生虫。
The ecological and epidemiological processes underlying the success of parasites competing within individual hosts are not yet clear. We investigated one idea: that increasing one parasite's infectious dose might decrease the success of its competitor. We reared uninfected larvae of the mosquito Aedes aegypti and exposed them to two concentrations of the microsporidium Vavraia culicis and of the protozoan Ascogregarina culicis. The rate at which Vavraia produced its infectious spores depended on its dose and that of its competitor: when the dose of Vavraia was high, only the higher dose of Ascogregarina slowed the production of spores, but when the dose was low, either dose of Ascogregarina did. Ascogregarina was least likely to produce oocysts when its competitor's dose was high and the mosquito was reared with little food. This was due to the mosquito's preadult mortality induced by Vavraia. Our results show that increasing the dose of a parasite can increase its deleterious effects on a coinfecting parasite. Since dose increases with a parasite's prevalence, such dose effects could lead to an epidemiological feedback that ultimately eliminates one of the parasites.