On the Fly: Interactions between Birds, Mosquitoes, and Environment That Have Molded West Nile Virus Genomic Structure over Two Decades

Nisha K. Duggal, Kate E. Langwig, Gregory D. Ebel, Aaron C. Brault

Research output: Contribution to journalReview article

2 Scopus citations

Abstract

West Nile virus (WNV) was first identified in North America almost 20 yr ago. In that time, WNV has crossed the continent and established enzootic transmission cycles, resulting in intermittent outbreaks of human disease that have largely been linked with climatic variables and waning avian seroprevalence. During the transcontinental dissemination of WNV, the original genotype has been displaced by two principal extant genotypes which contain an envelope mutation that has been associated with enhanced vector competence by Culex pipiens L. (Diptera: Culicidae) and Culex tarsalis Coquillett vectors. Analyses of retrospective avian host competence data generated using the founding NY99 genotype strain have demonstrated a steady reduction in viremias of house sparrows over time. Reciprocally, the current genotype strains WN02 and SW03 have demonstrated an inverse correlation between house sparrow viremia magnitude and the time since isolation. These data collectively indicate that WNV has evolved for increased avian viremia while house sparrows have evolved resistance to the virus such that the relative host competence has remained constant. Intrahost analyses of WNV evolution demonstrate that selection pressures are avian species-specific and purifying selection is greater in individual birds compared with individual mosquitoes, suggesting that the avian adaptive and/or innate immune response may impose a selection pressure on WNV. Phylogenomic, experimental evolutionary systems, and models that link viral evolution with climate, host, and vector competence studies will be needed to identify the relative effect of different selective and stochastic mechanisms on viral phenotypes and the capacity of newly evolved WNV genotypes for transmission in continuously changing landscapes.

Original languageEnglish (US)
Pages (from-to)1467-1474
Number of pages8
JournalJournal of medical entomology
Volume56
Issue number6
DOIs
StatePublished - Oct 28 2019
Externally publishedYes

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Keywords

  • Arboviral Molecular Biology
  • arboviral transmission
  • Arbovirology
  • Virology
  • West Nile virus

ASJC Scopus subject areas

  • Parasitology
  • veterinary(all)
  • Insect Science
  • Infectious Diseases

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