The evolution of virulence in a vector borne disease

人类直接感受到传染病的影响，特别是在发展中国家，传染病会导致疾病，有时甚至死亡。此外，最近发生的口蹄疫等流行病突出表明了传染病对发达国家农业的重要性。生态学家也越来越意识到寄生虫在调节许多自然种群和群落方面也很重要。疾病，特别是一种以上宿主共有的疾病，也越来越多地与许多濒危物种的减少有关。因此，我们需要了解为什么寄生虫会造成伤害（毒性）。这个项目将开发一个模型系统，我们可以在其中测试许多宿主寄生虫进化的理论。传染病病原体如病毒通常具有比其宿主短得多的世代时间。不仅如此，它们拥有庞大的种群，而且由于它们也倾向于快速突变，因此它们的种群内存在巨大的变异潜力。这意味着它们可以在进化过程中迅速变化。理论工作已经发展，预测在各种情况下的毒力的变化。这项工作着眼于寄生虫在宿主体内繁殖的速度。高生长率导致高传播，但也对宿主造成更多损害，因此具有更高的毒力。从寄生虫和宿主的角度来看，毒力被视为增加传播的不幸副产品。到目前为止，还没有多少数据来验证这些假设。该建议的主要目标是使用蜜蜂-螨-病毒相互作用作为一个新的模型系统，以提供病毒毒力进化理论的第一个实证检验。

The effect of infectious diseases is directly felt by humans in terms of illness and sometimes death, in particular in developing countries. Furthermore, recent epidemics such as foot and mouth have emphasized the importance of infectious diseases for agriculture in the developed world. Ecologists are also increasingly realising that parasites are also important in regulating many natural populations and communities. Disease, and in particular disease that is shared between more than one host are also increasingly implicated in the decline of many endangered species. We therefore need to understand why parasites casue the harm (virulence) that they do. This project will develop a model system in which we can test many of the theories of host parasite evolution. Infectious disease agents such as viruses typically have much shorter generation times than their hosts. Not only this they have huge populations and since they also tend to mutate rapidly, there is a vast potential for variation within their populations. This means that they can change rapidly through evolutionary time. Theoretical work has been developed that predicts changes in virulence under a wide range of situations. This work looks at how quickly the parasite reproduces in the host. High growth rate leads to high transmission but also causes more damage to the host and therefore higher virulence. Virulence is seen as an unfortunate by product from the point of view of both the parasite and the host, of increased transmission. As yet there is relatively little data that tests these assumptions. The key goal of this proposal is to use the honeybee-mite-viral interaction as a new model system to provide one of the first empirical tests of the evolutionary theory of viral virulence.