TY - JOUR
T1 - Molecular evolution of eastern equine encephalomyelitis virus in North America
AU - Weaver, Scott C.
AU - Scott, Thomas W.
AU - Rico-Hesse, Rebeca
N1 - Funding Information:
We thank James Strauss and John Holland for helpful advice concerning the manuscript, Pat Repik for providing some primers and virus stocks, and Julie Strizki for assistance with tissue culture. This research was supported by National Institutes of Health Grants A126787, A127779, and A110984, and the Maryland Agricultural Experiment Station.
PY - 1991/6
Y1 - 1991/6
N2 - We examined the rate and spatial pattern of eastern equine encephalomyelitis virus (EEEV) evolution in North America using primer-extension sequencing of viral RNA. Nucleotide sequences of the entire 26 S structural gene region of four EEEV strains revealed remarkable conservation between 1933 and 1985, with an estimated 0.7% divergence or 1.4 × 10-4 nucleotide substitutions per site per year. Sequences from smaller 26 S regions of nine additional strains suggested that EEEV evolves in North America in a single lineage, with genetic exchange regularly occurring among enzootic transmission foci. In these limited 26 S genome regions, only synonymous nucleotide substitutions became fixed between 1933 and 1988, implying a high degree of conservation in protein structure. Short nucleotide sequences from a Panamanian, South American variety isolate revealed a relatively distant relationship to North American serotype viruses. This suggested genetic divergence between antigenic varieties, and independent evolution of EEEV in North and South America. Factors related to replication and epidemiology of EEEV, which may constrain its evolution in nature, are discussed. Possible mechanisms of genetic exchange among enzootic foci are also considered.
AB - We examined the rate and spatial pattern of eastern equine encephalomyelitis virus (EEEV) evolution in North America using primer-extension sequencing of viral RNA. Nucleotide sequences of the entire 26 S structural gene region of four EEEV strains revealed remarkable conservation between 1933 and 1985, with an estimated 0.7% divergence or 1.4 × 10-4 nucleotide substitutions per site per year. Sequences from smaller 26 S regions of nine additional strains suggested that EEEV evolves in North America in a single lineage, with genetic exchange regularly occurring among enzootic transmission foci. In these limited 26 S genome regions, only synonymous nucleotide substitutions became fixed between 1933 and 1988, implying a high degree of conservation in protein structure. Short nucleotide sequences from a Panamanian, South American variety isolate revealed a relatively distant relationship to North American serotype viruses. This suggested genetic divergence between antigenic varieties, and independent evolution of EEEV in North and South America. Factors related to replication and epidemiology of EEEV, which may constrain its evolution in nature, are discussed. Possible mechanisms of genetic exchange among enzootic foci are also considered.
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U2 - 10.1016/0042-6822(91)90618-L
DO - 10.1016/0042-6822(91)90618-L
M3 - Article
C2 - 2024496
AN - SCOPUS:0025756466
SN - 0042-6822
VL - 182
SP - 774
EP - 784
JO - Virology
JF - Virology
IS - 2
ER -