Dpto Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), José Gutiérrez Abascal 2, 28006 Madrid, Spain.
BMC Evol Biol. 2010 Nov 10;10:347. doi: 10.1186/1471-2148-10-347.
Rabbit haemorrhagic disease virus (RHDV) is a highly virulent calicivirus, first described in domestic rabbits in China in 1984. RHDV appears to be a mutant form of a benign virus that existed in Europe long before the first outbreak. In the Iberian Peninsula, the first epidemic in 1988 severely reduced the populations of autochthonous European wild rabbit. To examine the evolutionary history of RHDV in the Iberian Peninsula, we collected virus samples from wild rabbits and sequenced a fragment of the capsid protein gene VP60. These data together with available sequences from other Western European countries, were analyzed following Bayesian Markov chain Monte Carlo methods to infer their phylogenetic relationships, evolutionary rates and demographic history.
Evolutionary relationships of RHDV revealed three main lineages with significant phylogeographic structure. All lineages seem to have emerged at a common period of time, between ~1875 and ~1976. The Iberian Peninsula showed evidences of genetic isolation, probably due to geographic barriers to gene flow, and was also the region with the youngest MRCA.Overall, demographic analyses showed an initial increase and stabilization of the relative genetic diversity of RHDV, and a subsequent reduction in genetic diversity after the first epidemic breakout in 1984, which is compatible with a decline in effective population size.
Results were consistent with the hypothesis that the current Iberian RHDV arose from a single infection between 1869 and 1955 (95% HPD), and rendered a temporal pattern of appearance and extinction of lineages. We propose that the rising positive selection pressure observed throughout the history of RHDV is likely mediated by the host immune system as a consequence of the genetic changes that rendered the virus virulent. Consequently, this relationship is suggested to condition RHDV demographic history.
兔出血症病毒（RHDV）是一种高致病性杯状病毒，于 1984 年在中国首次在家兔中发现。RHDV 似乎是一种良性病毒的突变体，早在第一次爆发之前就存在于欧洲。在伊比利亚半岛，1988 年的第一次流行严重减少了当地欧洲野兔的数量。为了研究 RHDV 在伊比利亚半岛的进化历史，我们从野生兔中采集了病毒样本，并对衣壳蛋白基因 VP60 的一个片段进行了测序。这些数据与来自其他西欧国家的可用序列一起，采用贝叶斯马尔可夫链蒙特卡罗方法进行分析，以推断它们的系统发育关系、进化率和种群历史。
RHDV 的进化关系显示出三个具有显著系统地理结构的主要谱系。所有谱系似乎都在同一时期出现，大约在 1875 年至 1976 年之间。伊比利亚半岛显示出遗传隔离的证据，可能是由于基因流动的地理障碍，也是具有最年轻共同祖先的地区。总体而言，人口统计学分析显示 RHDV 的相对遗传多样性最初增加并稳定，然后在 1984 年第一次流行爆发后减少，这与有效种群数量的减少相吻合。
结果与假设一致，即当前伊比利亚 RHDV 是在 1869 年至 1955 年之间的一次单一感染中产生的（95% HPD），并呈现出线粒体的出现和灭绝的时间模式。我们提出，在 RHDV 的历史上观察到的持续正向选择压力可能是由病毒的遗传变化使病毒具有致病性，从而导致宿主免疫系统介导的。因此，这种关系被认为是 RHDV 种群历史的条件。
