Sorci G
Biogéosciences, CNRS UMR 6282, Université de Bourgogne, Dijon, France.
Parasite Immunol. 2013 Nov;35(11):350-61. doi: 10.1111/pim.12047.
Interacting pathogens and hosts have evolved reciprocal adaptations whose function is to allow host exploitation (from the pathogen stand point) or minimize the cost of infection (from the host stand point). Once infected, two strategies are offered to the host: parasite clearing (resistance) and withstanding the infection while paying a low fitness cost (tolerance). In both cases, the immune system plays a central role. Interestingly, whatever the defence strategy adopted by the host, this is likely to have an effect on parasite evolution. Given their short generation time and large population size, parasites are expected to rapidly adapt to the environmental conditions provided by their hosts. The immune system can therefore represent a powerful engine of parasite evolution, with the direction of such evolutionary trajectory depending on, among other factors, (i) the type of mechanism involved (resistance or tolerance) and (ii) the damage induced by overreacting immune defences. In this article, I will discuss these different issues focusing on selected examples of recent work conducted on two bird pathogens, the protozoa responsible for avian malaria (Plasmodium sp.) and the bacterium Mycoplasma gallisepticum.
相互作用的病原体和宿主已经进化出相互适应的机制，其作用是从病原体的角度实现对宿主的利用，或者从宿主的角度将感染成本降至最低。一旦被感染，宿主可以采取两种策略：清除寄生虫（抗性）和在付出较低适应性代价的情况下耐受感染（耐受性）。在这两种情况下，免疫系统都起着核心作用。有趣的是，无论宿主采取何种防御策略，这都可能对寄生虫的进化产生影响。鉴于寄生虫的世代时间短且种群数量大，预计它们会迅速适应宿主提供的环境条件。因此，免疫系统可能是寄生虫进化的强大驱动力，这种进化轨迹的方向取决于多种因素，其中包括：（i）所涉及的机制类型（抗性或耐受性），以及（ii）免疫防御过度反应所造成的损害。在本文中，我将围绕对两种鸟类病原体开展的近期研究的选定实例来讨论这些不同的问题，这两种病原体分别是引起禽类疟疾的原生动物（疟原虫属）和鸡败血支原体。
