title: Genetic variation of St. Louis encephalitis virus.
abstract: St. Louis encephalitis virus (SLEV) has been regularly isolated throughout the Americas since 1933. Previous phylogenetic studies involving 62 isolates have defined seven major lineages (I-VII), further divided into 14 clades. In this study, 28 strains isolated in Texas in 1991 and 2001-2003, and three older, previously unsequenced strains from Jamaica and California were sequenced over the envelope protein gene. The inclusion of these new sequences, and others published since 2001, has allowed better delineation of the previously published SLEV lineages, in particular the clades of lineage II. Phylogenetic analysis of 106 isolates identified 13 clades. All 1991 and 2001-2003 isolates from Nueces, Jefferson and Harris Counties (Texas Gulf Coast) group in clade IIB with other isolates from these counties isolated during the 1980s and 1990s. This lack of evidence for introduction of novel strains into the Texas Gulf Coast over a long period of time is consistent with overwintering of SLEV in this region. Two El Paso isolates, both from 2002, group in clade VA with recent Californian isolates from 1998-2001 and some South American strains with a broad temporal range. Overall, these data are consistent with multiple introductions of SLEV from South America into North America, and provide support for the hypothesis that in most situations, SLEV circulates within a locality, with occasional incursions from other areas. Finally, SLEV has much lower nucleotide (10.1 %) and amino acid variation (2.8 %) than other members of the Japanese encephalitis virus complex (maximum variation 24.6 % nucleotide and 11.8 % amino acid).
authors.affiliation: Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
authors.forename: Fiona J
authors.initials: FJ
authors.lastname: May
authors.affiliation: Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
authors.forename: Shuliu
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
authors.forename: Hilda
authors.initials: H
authors.lastname: Guzman
authors.affiliation: Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
authors.forename: David W C
authors.initials: DWC
authors.lastname: Beasley
authors.affiliation: Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Tesh
authors.affiliation: Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Higgs
authors.affiliation: Texas Department of State Health Services, Austin, TX, USA.
authors.forename: Pushker
authors.initials: P
authors.lastname: Raj
authors.affiliation: Harris County Public Health and Environmental Services, Mosquito Control Division, 3330 Old Spanish Trail, Houston, TX 77021, USA.
authors.forename: Rudy
authors.initials: R
authors.lastname: Bueno
authors.affiliation: Harris County Public Health and Environmental Services, Mosquito Control Division, 3330 Old Spanish Trail, Houston, TX 77021, USA.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Randle
authors.affiliation: Laboratory Medicine, Philadelphia VA Medical Center, 3900 Woodland Avenue, Philadelphia, PA 19104, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Chandler
authors.affiliation: Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555-0609, USA.
authors.forename: Alan D T
authors.initials: ADT
authors.lastname: Barrett
mesh_terms: D002140:California / Q000453:epidemiology; D004665:Encephalitis Virus, St. Louis / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D004674:Encephalitis, St. Louis / Q000453:epidemiology* / Q000821:virology; D014644:Genetic Variation; D006801:Humans; D007563:Jamaica / Q000453:epidemiology; D008958:Models, Molecular; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013781:Texas / Q000453:epidemiology; D014759:Viral Envelope Proteins / Q000235:genetics*
chemical_list: D014759:Viral Envelope Proteins