Insights into the Evolutionary History of an Emerging Livestock Pathogen: Porcine Circovirus 2
Insights into the Evolutionary History of an Emerging Livestock Pathogen: Porcine Circovirus 2
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DOI：
10.1128/jvi.01719-09
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发表时间：
2009-12-15
影响因子：
5.4
通讯作者：
Holmes, Edward C.
中科院分区：
文献类型：
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作者：
Firth, Cadhla;Charleston, Michael A.;Holmes, Edward C.
猪圆环病毒2型（Porcine Circovirus 2，PCV 2）是断奶后多系统衰竭综合征（Postweaning Multisystemic Wasting Syndrome，PMWS）的主要病原。毒力PCV 2在20世纪90年代北美和欧洲几乎同时爆发PMWS后首次被发现，此后实现了全球分布。然而，对PCV 2的出现和传播的过程仍然知之甚少。在这里，系统发育和cophylogenetic推断被用来解决关键问题的时间尺度，过程和地理扩散的新出现的PCV 2。这些分析的结果表明，两种基因型的PCV 2（PCV 2a和PCV 2b）可能已经出现了从一个共同的祖先大约100年前，并已独立的进化轨迹，自那时以来，尽管在相同的宿主物种和地理区域共循环。我们发现的PCV 2地理移动模式似乎与全球生猪贸易的模式相似，并表明无症状动物的移动可能促进了强毒PCV 2在地球仪周围的快速传播。我们进一步估计PCV 2的核苷酸替换率为1.2 × 10（-3）替换/位点/年，这是单链DNA病毒的最高记录。这种高进化速率可能使PCV 2保持更接近单链RNA病毒而不是双链DNA病毒的进化动力学，进一步促进PCV 2在全球范围内的快速出现。
Porcine circovirus 2 (PCV2) is the primary etiological agent of postweaning multisystemic wasting syndrome (PMWS), one of the most economically important emerging swine diseases worldwide. Virulent PCV2 was first identified following nearly simultaneous outbreaks of PMWS in North America and Europe in the 1990s and has since achieved global distribution. However, the processes responsible for the emergence and spread of PCV2 remain poorly understood. Here, phylogenetic and cophylogenetic inferences were utilized to address key questions on the time scale, processes, and geographic diffusion of emerging PCV2. The results of these analyses suggest that the two genotypes of PCV2 (PCV2a and PCV2b) are likely to have emerged from a common ancestor approximately 100 years ago and have been on independent evolutionary trajectories since that time, despite cocirculating in the same host species and geographic regions. The patterns of geographic movement of PCV2 that we recovered appear to mimic those of the global pig trade and suggest that the movement of asymptomatic animals is likely to have facilitated the rapid spread of virulent PCV2 around the globe. We further estimated the rate of nucleotide substitution for PCV2 to be on the order of 1.2 x 10(-3) substitutions/site/year, the highest yet recorded for a single-stranded DNA virus. This high rate of evolution may allow PCV2 to maintain evolutionary dynamics closer to those of single-stranded RNA viruses than to those of double-stranded DNA viruses, further facilitating the rapid emergence of PCV2 worldwide.