Holmes E C, Drummond A J
Center for Infectious Disease Dynamics, Department of Biology, Mueller Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.
Curr Top Microbiol Immunol. 2007;315:51-66. doi: 10.1007/978-3-540-70962-6_3.
Despite the wealth of data describing the ecological factors that underpin viral emergence, little is known about the evolutionary processes that allow viruses to jump species barriers and establish productive infections in new hosts. Understanding the evolutionary basis to virus emergence is therefore a key research goal and many of the debates in this area can be considered within the rigorous theoretical framework established by evolutionary genetics. In particular, the respective roles played by natural selection and genetic drift in shaping genetic diversity are also of fundamental importance for understanding the nature of viral emergence. Herein, we discuss whether there are evolutionary rules to viral emergence, and especially whether certain types of virus, or those that infect a particular type of host species, are more likely to emerge than others. We stress the complex interplay between rates of viral evolution and the ability to recognize cell receptors from phylogenetically divergent host species. We also emphasize the current lack of convincing data as to whether viral emergence requires adaptation to the new host species during the early stages of infection, or whether it is largely a chance process involving the transmission of a viral strain with the necessary genetic characteristics.
尽管有大量数据描述了促成病毒出现的生态因素，但对于使病毒跨越物种屏障并在新宿主中建立有效感染的进化过程却知之甚少。因此，了解病毒出现的进化基础是一个关键的研究目标，并且该领域的许多争论都可以在进化遗传学建立的严格理论框架内进行考量。特别是，自然选择和遗传漂变在塑造遗传多样性中所起的各自作用，对于理解病毒出现的本质也至关重要。在此，我们讨论病毒出现是否存在进化规律，尤其是某些类型的病毒，或者那些感染特定类型宿主物种的病毒，是否比其他病毒更有可能出现。我们强调病毒进化速率与从系统发育上不同的宿主物种识别细胞受体能力之间的复杂相互作用。我们还强调，目前缺乏令人信服的数据来表明病毒出现是否需要在感染早期适应新的宿主物种，或者它在很大程度上是否是一个涉及传播具有必要遗传特征的病毒株的偶然过程。
