title: Genetic diversity and purifying selection in West Nile virus populations are maintained during host switching.
abstract: To investigate differential evolutionary rates and selective forces of WNV in hosts and vectors, we measured the genetic diversity that arose during alternating passage in mosquitoes and birds. Within-host genetic diversity was monitored in each of three experimentally passed replicates, and the complete genome sequence of each WNV strain was determined after passage. The intrahost genetic diversity that arose during alternating passage was significantly greater than the diversity generated during chicken-only passage and similar to mosquito-only passage. dN/dS ratios suggested purifying selection similar to chick-passed virus, but not to mosquito-passed virus. Thus, the abundant genetic variation contributed to WNV populations through infection of mosquitoes and the strong purifying selection contributed by infection of birds may be maintained despite frequent host switching.
authors.affiliation: Wadsworth Center, New York State Department of Health, 5668 State Farm Rd. Slingerlands, NY 12159, USA.
authors.forename: Greta V S
authors.initials: GV
authors.lastname: Jerzak
authors.forename: Ivy
authors.initials: I
authors.lastname: Brown
authors.forename: Pei-Yong
authors.initials: PY
authors.lastname: Shi
authors.forename: Laura D
authors.initials: LD
authors.lastname: Kramer
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Ebel
mesh_terms: D000818:Animals; D002460:Cell Line; D002645:Chickens / Q000821:virology; D006224:Cricetinae; D003465:Culex / Q000821:virology; D005260:Female; D014644:Genetic Variation; D016679:Genome, Viral; D054884:Host-Pathogen Interactions; D010802:Phylogeny; D011201:Poultry Diseases / Q000821:virology; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D012692:Serial Passage; D013045:Species Specificity; D013047:Specific Pathogen-Free Organisms; D014901:West Nile Fever / Q000662:veterinary / Q000821:virology*; D014902:West Nile virus / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity*