title: Envelope and pre-membrane protein structural amino acid mutations mediate diminished avian growth and virulence of a Mexican West Nile virus isolate.
abstract: The hallmark attribute of North American West Nile virus (WNV) strains has been high pathogenicity in certain bird species. Surprisingly, this avian virulent WNV phenotype has not been observed during its geographical expansion into the Caribbean, Central America and South America. One WNV variant (TM171-03-pp1) isolated in Mexico has demonstrated an attenuated phenotype in two widely distributed North American bird species, American crows (AMCRs) and house sparrows (HOSPs). In order to identify genetic determinants associated with attenuated avian replication of the TM171-03-pp1 variant, chimeric viruses between the NY99 and Mexican strains were generated, and their replicative capacity was assessed in cell culture and in AMCR, HOSP and house finch avian hosts. The results demonstrated that mutations in both the pre-membrane (prM-I141T) and envelope (E-S156P) genes mediated the attenuation phenotype of the WNV TM171-03-pp1 variant in a chicken macrophage cell line and in all three avian species assayed. Inclusion of the prM-I141T and E-S156P TM171-03-pp1 mutations in the NY99 backbone was necessary to achieve the avian attenuation level of the Mexican virus. Furthermore, reciprocal incorporation of both prM-T141I and E-P156S substitutions into the Mexican virus genome was necessary to generate a virus that exhibited avian virulence equivalent to the NY99 virus. These structural changes may indicate the presence of new evolutionary pressures exerted on WNV populations circulating in Latin America or may signify a genetic bottleneck that has constrained their epiornitic potential in alternative geographical locations.
authors.affiliation: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Stanley A
authors.initials: SA
authors.lastname: Langevin
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Bowen
authors.affiliation: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Wanichaya N
authors.initials: WN
authors.lastname: Ramey
authors.affiliation: Colorado Division of Wildlife, Fort Collins, CO 80526, USA.
authors.forename: Todd A
authors.initials: TA
authors.lastname: Sanders
authors.affiliation: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Payal D
authors.initials: PD
authors.lastname: Maharaj
authors.affiliation: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Jennine
authors.initials: J
authors.lastname: Cornelius
authors.affiliation: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Barker
authors.affiliation: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: William K
authors.initials: WK
authors.lastname: Reisen
authors.affiliation: Departments of Pathology and Microbiology and Immunology, Center for Emerging Infectious Diseases and Biodefense, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA.
authors.forename: David W C
authors.initials: DWC
authors.lastname: Beasley
authors.affiliation: Departments of Pathology and Microbiology and Immunology, Center for Emerging Infectious Diseases and Biodefense, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA.
authors.forename: Alan D T
authors.initials: ADT
authors.lastname: Barrett
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Kinney
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA.
authors.forename: Claire Y-H
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA.|Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Brault
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001715:Bird Diseases / Q000821:virology; D002460:Cell Line; D002645:Chickens; D003001:Cloning, Molecular; D046368:Crows / Q000821:virology*; D018076:DNA, Complementary / Q000235:genetics; D046369:Finches / Q000821:virology*; D008565:Membrane Proteins / Q000235:genetics; D008800:Mexico; D009154:Mutation; D010641:Phenotype; D058974:Phylogeography; D010957:Plasmids / Q000235:genetics; D017422:Sequence Analysis, DNA; D046370:Sparrows / Q000821:virology*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D019562:Viral Load; D014774:Virulence; D014779:Virus Replication; D014902:West Nile virus / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity
chemical_list: D018076:DNA, Complementary; D008565:Membrane Proteins; D014759:Viral Envelope Proteins