Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
J. Craig Venter Institute, Rockville, Maryland, USA.
J Virol. 2018 May 29;92(12). doi: 10.1128/JVI.00074-18. Print 2018 Jun 15.
Eastern equine encephalitis virus (EEEV) has a high case-fatality rate in horses and humans, and Florida has been hypothesized to be the source of EEEV epidemics for the northeastern United States. To test this hypothesis, we sequenced complete genomes of 433 EEEV strains collected within the United States from 1934 to 2014. Phylogenetic analysis suggested EEEV evolves relatively slowly and that transmission is enzootic in Florida, characterized by higher genetic diversity and long-term local persistence. In contrast, EEEV strains in New York and Massachusetts were characterized by lower genetic diversity, multiple introductions, and shorter local persistence. Our phylogeographic analysis supported a source-sink model in which Florida is the major source of EEEV compared to the other localities sampled. In sum, this study revealed the complex epidemiological dynamics of EEEV in different geographic regions in the United States and provided general insights into the evolution and transmission of other avian mosquito-borne viruses in this region. Eastern equine encephalitis virus (EEEV) infections are severe in horses and humans on the east coast of the United States with a >90% mortality rate in horses, an ∼33% mortality rate in humans, and significant brain damage in most human survivors. However, little is known about the evolutionary characteristics of EEEV due to the lack of genome sequences. By generating large collection of publicly available complete genome sequences, this study comprehensively determined the evolution of the virus, described the epidemiological dynamics of EEEV in different states in the United States, and identified Florida as one of the major sources. These results may have important implications for the control and prevention of other mosquito-borne viruses in the Americas.
东部马脑炎病毒（EEEV）在马和人中的病死率很高，佛罗里达州被认为是美国东北部 EEEV 流行的源头。为了验证这一假设，我们对 1934 年至 2014 年间在美国采集的 433 株 EEEV 株进行了全基因组测序。系统进化分析表明，EEEV 进化相对较慢，其在佛罗里达州呈地方性流行，具有较高的遗传多样性和长期的地方持续性。相比之下，纽约州和马萨诸塞州的 EEEV 株具有较低的遗传多样性、多次传入和较短的地方持续性。我们的系统地理分析支持了一个源汇模型，即在佛罗里达州与其他采样地点相比，是 EEEV 的主要来源。总之，本研究揭示了美国不同地理区域 EEEV 的复杂流行动态，并为了解该地区其他禽媒病毒的进化和传播提供了一般性认识。在美国东海岸，EEEV 感染对马和人都很严重，马的病死率超过 90%，人的病死率约为 33%，大多数幸存者都有严重的脑损伤。然而，由于缺乏基因组序列，人们对 EEEV 的进化特征知之甚少。本研究通过生成大量公开的全基因组序列，全面确定了病毒的进化，描述了美国不同州的 EEEV 流行动态，并确定佛罗里达州是主要来源之一。这些结果可能对美洲其他蚊媒病毒的控制和预防具有重要意义。
