Exploring Genomic, Geographic and Virulence Interactions among Epidemic and Non-Epidemic St. Louis Encephalitis Virus (Flavivirus) Strains

PLoS One. 2015 Aug 27;10(8):e0136316. doi: 10.1371/journal.pone.0136316. eCollection 2015.

Abstract

St. Louis encephalitis virus (SLEV) is a re-emerging arbovirus in South America. In 2005, an encephalitis outbreak caused by SLEV was reported in Argentina. The reason for the outbreak remains unknown, but may have been related to virological factors, changes in vectors populations, avian amplifying hosts, and/or environmental conditions. The main goal of this study was to characterize the complete genome of epidemic and non-epidemic SLEV strains from Argentina. Seventeen amino acid changes were detected; ten were non-conservative and located in proteins E, NS1, NS3 and NS5. Phylogenetic analysis showed two major clades based on geography: the North America and northern Central America (NAnCA) clade and the South America and southern Central America (SAsCA) clade. Interestingly, the presence of SAsCA genotype V SLEV strains in the NAnCA clade was reported in California, Florida and Texas, overlapping with known bird migration flyways. This work represents the first step in understanding the molecular mechanisms underlying virulence and biological variation among SLEV strains.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Argentina
  • Chlorocebus aethiops
  • Communicable Diseases, Emerging / epidemiology
  • Communicable Diseases, Emerging / genetics*
  • Encephalitis Virus, St. Louis* / genetics
  • Encephalitis Virus, St. Louis* / pathogenicity
  • Encephalitis, St. Louis / epidemiology
  • Encephalitis, St. Louis / genetics*
  • Genome, Viral*
  • Genotype
  • Humans
  • Phylogeny*
  • United States / epidemiology
  • Vero Cells
  • Viral Proteins / genetics*

Substances

  • Viral Proteins

Grants and funding

This project was supported by Agencia Nacional de Promoción Cientifica y Tecnológica, Fondo Nacional de Ciencia y Tecnología (ANPCYT-FONCYT) Grant number 2010/38060 and 2013/1779 (www.agencia.mincyt.gob.ar), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) (www.conicet.gov.ar), Secretaría de Ciencia y Técnica -Universidad Nacional de Córdoba (SECYT-UNC) (http://www.unc.edu.ar/investigacion/cienciaytecnologia/novedades-informacion-cyt), International Society for Infectious Diseases (http://www.isid.org/), UNESCO-IUMS-SGM (United Nations Educational, Scientific and Cultural Organization, International Union Microbiology Societies-Society of General Microbiology) (http://www.iums.org/), Bunge y Born Foundation (FBBEI8/10) (http://www.fundacionbyb.org), and the US Centers for Disease Control and Prevention (www.cdc.gov). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.