title: Host competence and helicase activity differences exhibited by West Nile viral variants expressing NS3-249 amino acid polymorphisms.
abstract: A single helicase amino acid substitution, NS3-T249P, has been shown to increase viremia magnitude/mortality in American crows (AMCRs) following West Nile virus (WNV) infection. Lineage/intra-lineage geographic variants exhibit consistent amino acid polymorphisms at this locus; however, the majority of WNV isolates associated with recent outbreaks reported worldwide have a proline at the NS3-249 residue. In order to evaluate the impact of NS3-249 variants on avian and mammalian virulence, multiple amino acid substitutions were engineered into a WNV infectious cDNA (NY99; NS3-249P) and the resulting viruses inoculated into AMCRs, house sparrows (HOSPs) and mice. Differential viremia profiles were observed between mutant viruses in the two bird species; however, the NS3-249P virus produced the highest mean peak viral loads in both avian models. In contrast, this avian modulating virulence determinant had no effect on LD50 or the neurovirulence phenotype in the murine model. Recombinant helicase proteins demonstrated variable helicase and ATPase activities; however, differences did not correlate with avian or murine viremia phenotypes. These in vitro and in vivo data indicate that avian-specific phenotypes are modulated by critical viral-host protein interactions involving the NS3-249 residue that directly influence transmission efficiency and therefore the magnitude of WNV epizootics in nature.
authors: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America.
authors: Stanley A
authors: SA
authors: Langevin
authors: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America.
authors: Richard A
authors: RA
authors: Bowen
authors: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America.
authors: William K
authors: WK
authors: Reisen
authors: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America.
authors: Christy C
authors: CC
authors: Andrade
authors: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America.
authors: Wanichaya N
authors: WN
authors: Ramey
authors: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America.
authors: Payal D
authors: PD
authors: Maharaj
authors: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America.
authors: Michael
authors: M
authors: Anishchenko
authors: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America.
authors: Joan L
authors: JL
authors: Kenney
authors: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America.
authors: Nisha K
authors: NK
authors: Duggal
authors: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America.
authors: Hannah
authors: H
authors: Romo
authors: Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America.
authors: Aloke Kumar
authors: AK
authors: Bera
authors: United States Fish and Wildlife Service, Portland, Oregon, United States of America.
authors: Todd A
authors: TA
authors: Sanders
authors: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America; Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America.
authors: Angela
authors: A
authors: Bosco-Lauth
authors: Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America.
authors: Janet L
authors: JL
authors: Smith
authors: Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America.
authors: Richard
authors: R
authors: Kuhn
authors: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, United States of America; Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America.
authors: Aaron C
authors: AC
authors: Brault
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002522:Chlorocebus aethiops; D046368:Crows / Q000821:virology; D058507:Host Specificity; D051379:Mice; D008969:Molecular Sequence Data; D020641:Polymorphism, Single Nucleotide; D020365:RNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D046370:Sparrows / Q000821:virology; D014709:Vero Cells; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014774:Virulence / Q000235:genetics; D014902:West Nile virus / Q000235:genetics* / Q000472:pathogenicity; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D020365:RNA Helicases; D012697:Serine Endopeptidases; D017361:Viral Nonstructural Proteins; C060028:NS3 protein, flavivirus; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases