title: Phylogenetic analysis of WNV in North American blood donors during the 2003-2004 epidemic seasons.
abstract: West Nile Virus (WNV) collected from 179 human blood donors in 25 US states and three Canadian provinces during the 2003 and 2004 epidemic seasons were genetically analyzed. The evolution of WNV during its Western spread was examined by envelope (E) gene sequencing of all 179 cases and full open reading frame sequencing of a subset of 20 WNV to determine if geographic and temporal segregation of distinct viral variants had occurred. Median joining network analysis was used to examine the genetic relationship between E gene variants and identified four large genetic clusters showing the gradual accumulation of mutations during the virus' western expansion. Two related WNV variants and their descendents, undetected in prior years, expanded in frequency. Apparent founder effects were observed in some regional outbreaks possibly due to local WNV colonization by a limited number of viruses. Amino acid mutations associated with newly expanding genetic variants reflect either selectively neutral mutational drift and/or mutations providing replicative advantages over the previously dominant forms of WNV.
authors.affiliation: Blood Systems Research Institute, San Francisco, CA 94118, USA.
authors.forename: Belinda L
authors.initials: BL
authors.lastname: Herring
authors.forename: Flavien
authors.initials: F
authors.lastname: Bernardin
authors.forename: Sally
authors.initials: S
authors.lastname: Caglioti
authors.forename: Susan
authors.initials: S
authors.lastname: Stramer
authors.forename: Leslie
authors.initials: L
authors.lastname: Tobler
authors.forename: William
authors.initials: W
authors.lastname: Andrews
authors.forename: Lawrence
authors.initials: L
authors.lastname: Cheng
authors.forename: Sarah
authors.initials: S
authors.lastname: Rampersad
authors.forename: Cherie
authors.initials: C
authors.lastname: Cameron
authors.forename: John
authors.initials: J
authors.lastname: Saldanha
authors.forename: Michael P
authors.initials: MP
authors.lastname: Busch
authors.forename: Eric
authors.initials: E
authors.lastname: Delwart
mesh_terms: D001782:Blood Donors; D004252:DNA Mutational Analysis; D019143:Evolution, Molecular; D015686:Gene Products, env / Q000235:genetics; D016679:Genome, Viral / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D009656:North America / Q000453:epidemiology; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D013997:Time Factors; D014901:West Nile Fever / Q000453:epidemiology* / Q000821:virology*; D014902:West Nile virus / Q000235:genetics* / Q000302:isolation & purification*
chemical_list: D015686:Gene Products, env