Lab of Ornithology, Cornell University, Ithaca, NY 14850, USA.
Proc Biol Sci. 2013 Sep 7;280(1766):20131068. doi: 10.1098/rspb.2013.1068.
Emergence of a new disease in a novel host is thought to be a rare outcome following frequent pathogen transfers between host species. However, few opportunities exist to examine whether disease emergence stems from a single successful pathogen transfer, and whether this successful lineage represents only one of several pathogen transfers between hosts. We examined the successful host transfer and subsequent evolution of the bacterial pathogen Mycoplasma gallisepticum, an emergent pathogen of house finches (Haemorhous (formerly Carpodacus) mexicanus). Our principal goals were to assess whether host transfer has been a repeated event between the original poultry hosts and house finches, whether only a single host transfer was ultimately responsible for the emergence of M. gallisepticum in these finches, and whether the spread of the pathogen from east to west across North America has resulted in spatial structuring in the pathogen. Using a phylogeny of M. gallisepticum based on 107 isolates from domestic poultry, house finches and other songbirds, we infer that the bacterium has repeatedly jumped between these two groups of hosts but with only a single lineage of M. gallisepticum persisting and evolving in house finches; bacterial evolution has produced monophyletic eastern and western North American subclades.
一种新疾病在新宿主中出现被认为是宿主间频繁病原体转移后罕见的结果。然而，很少有机会检查疾病的出现是否源于一次成功的病原体转移，以及该成功谱系是否仅代表宿主间的几次病原体转移之一。我们研究了细菌病原体鸡毒支原体在斑胸草雀（Haemorhous（原 Carpodacus）mexicanus）中的成功宿主转移和随后的进化。我们的主要目标是评估宿主转移是否在原始家禽宿主和斑胸草雀之间是一个重复的事件，是否只有一次宿主转移最终导致了鸡毒支原体在这些雀鸟中的出现，以及病原体从东向西跨越北美的传播是否导致了病原体的空间结构。利用基于来自家禽、斑胸草雀和其他鸣禽的 107 个分离株的鸡毒支原体系统发育树，我们推断该细菌在这两个宿主群之间反复跳跃，但只有一个鸡毒支原体谱系在斑胸草雀中持续存在和进化；细菌进化产生了单系的北美东部和西部亚群。
