The evolution of virulence in a vector borne disease

人类直接感受到传染病的影响，在疾病方面，有时甚至死亡，特别是在发展中国家。此外，最近的口蹄疫等流行病强调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，特别是在不止一个宿主之间共享的疾病，也越来越多地与许多濒危物种的衰落有关。因此，我们需要了解为什么寄生虫会造成它们所造成的危害(毒性)。这个项目将开发一个模型系统，在其中我们可以测试寄主寄生虫进化的许多理论。像病毒这样的传染病病原体的世代时间通常比它们的宿主短得多。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，它们的种群内存在巨大的变异潜力。这意味着它们可以随着进化时间的推移而迅速变化。理论工作已经发展起来，可以预测在各种情况下毒力的变化。这项研究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率，但也会对寄主造成更大的损害，从而产生更高的毒力。从寄生虫和宿主的角度来看，毒力被视为传播增加的不幸副产品。到目前为止，检验这些假设的数据相对较少。这项提议的关键目标是将蜜蜂-螨虫-病毒相互作用作为一种新的模型系统，为病毒毒力进化理论提供第一批经验测试之一。

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.