Cilnis M J, Kang W, Weaver S C
Department of Biology, University of California, San Diego, La Jolla 92093-0116, USA.
Virology. 1996 Apr 15;218(2):343-51. doi: 10.1006/viro.1996.0203.
We studied molecular evolution of the mosquito-borne alphavirus Highlands J (HJ) virus by sequencing PCR products generated from 19 strains isolated between 1952 and 1994. Sequences of 1200 nucleotides including portions of the E1 gene and the 3' untranslated region revealed a relatively slow evolutionary rate estimated at 0.9-1.6 x 10(-4) substitutions per nucleotide per year. Phylogenetic trees indicated that all HJ viruses descended from a common ancestor and suggested the presence of one dominant lineage in North America. However, two or more minor lineages probably circulated simultaneously for periods of years to a few decades. Strains isolated from a horse suffering encephalitis, and implicated in a recent turkey outbreak, were not phylogenetically distinct from strains isolated in other locations during the same time periods. Our findings are remarkably similar to those we obtained previously for another North American alphavirus, eastern equine encephalomyelitis virus, with which Highlands J shares primary mosquito and avian hosts, geographical distribution, and ecology. These results support the hypotheses that the duration of the transmission season affects arboviral evolutionary rates and vertebrate host mobility influences genetic diversity.
我们通过对1952年至1994年间分离出的19株病毒的PCR产物进行测序，研究了蚊媒甲病毒高地J（HJ）病毒的分子进化。包括E1基因部分和3'非翻译区在内的1200个核苷酸序列显示，其进化速率相对较慢，估计为每年每核苷酸0.9 - 1.6×10⁻⁴个替换。系统发育树表明，所有HJ病毒均源自一个共同祖先，并提示在北美存在一个主要谱系。然而，可能有两个或更多的次要谱系在数年至数十年的时间里同时传播。从一匹患脑炎的马身上分离出的、与近期火鸡疫情有关的毒株，在系统发育上与同一时期在其他地点分离出的毒株并无明显差异。我们的研究结果与之前我们对另一种北美甲病毒——东部马脑脊髓炎病毒的研究结果非常相似，高地J病毒与东部马脑脊髓炎病毒共有主要的蚊媒和禽类宿主、地理分布及生态环境。这些结果支持了以下假说：传播季节的时长会影响虫媒病毒的进化速率，而脊椎动物宿主的移动性会影响遗传多样性。
