Publications
Large scale complete genome sequencing and phylodynamic analysis of eastern equine encephalitis virus reveal source-sink transmission dynamics in the United States
Tan Y, Tsan-Yuk Lam T, Heberlein-Larson LA, Smole SC, Auguste AJ, Hennigan S, Halpin RA, Fedorova N, Puri V, Stockwell TB, Shilts MH, Andreadis T, Armstrong PM, Tesh RB, Weaver SC, Unnasch TR, Ciota AT, Kramer LD, Das SR
PMID: 29618651
Abstract
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 U.S. To test this hypothesis, we sequenced complete genomes of 433 EEEV strains collected within the U.S. 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 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 U.S., 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 over 90% mortality rate in horses, approximately 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 U.S., 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.