Evolutionary dynamics and spatial genetic structure of epizootic hemorrhagic disease virus in the eastern United States.
Epizootic hemorrhagic disease virus (EHDV) is a significant pathogen of wild and domestic ungulates worldwide. In North America, serotype EHDV-2 is responsible for the majority of outbreaks, which are most commonly observed in white-tailed deer. A recent study by Murphy et al. [Murphy, M.D., Howerth, E.W., MacLachlan, N.J., Stallknecht, D.E., 2005. Genetic variation among epizootic hemorrhagic disease viruses in the southeastern United States: 1978-2001. Infect. Genet. Evol. 5, 157-165] examined the genetic relationships of EHDV-2 sequences from outbreaks across the eastern United States for evidence of temporal and spatial structure but found no evidence for either. Here, I present results of further examination of the same data using additional types of analysis. Contrary to the earlier assessment, I find that for outbreaks observed within the same year, genetic and spatial distances are in fact positively correlated and that the virus is evolving at a rate similar to that seen in other vector-born RNA viruses. Estimates of demographic history further revealed that population sizes of the virus had remained relatively stable over most of its history. A noticeable exception to this trend was a recent demographic bottleneck, possibly associated with a selective sweep, that affected one of the two viral genes examined. These results demonstrate that genetic variation accumulating at selectively neutral and measurably evolving sites in the EHDV-2 genome can be employed to gain insights into the spatial and temporal dynamics of this viral pathogen.
Biek
Roman
R
Department of Biology and Center for Disease Ecology, 1510 Clifton Road, Emory University, Atlanta, GA 30322, USA. rbiek@emory.edu
D000820:Animal Diseases / Q000821:virology; D000818:Animals; D002519:Ceratopogonidae / Q000821:virology; D003670:Deer / Q000821:virology; D018164:Hemorrhagic Disease Virus, Epizootic / Q000235:genetics*; D007303:Insect Vectors / Q000821:virology; D010802:Phylogeny; D012088:Reoviridae Infections / Q000453:epidemiology / Q000821:virology; D013997:Time Factors; D014481:United States / Q000453:epidemiology