Molecular evolution of eastern equine encephalomyelitis virus in North America

Scott C. Weaver, Thomas W. Scott, Rebeca Rico-Hesse

    Research output: Contribution to journalArticle

    63 Scopus citations

    Abstract

    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.

    Original languageEnglish (US)
    Pages (from-to)774-784
    Number of pages11
    JournalVirology
    Volume182
    Issue number2
    DOIs
    StatePublished - Jun 1991

    ASJC Scopus subject areas

    • Virology

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