title: Recovery of West Nile Virus Envelope Protein Domain III Chimeras with Altered Antigenicity and Mouse Virulence.
abstract: Flaviviruses are positive-sense, single-stranded RNA viruses responsible for millions of human infections annually. The envelope (E) protein of flaviviruses comprises three structural domains, of which domain III (EIII) represents a discrete subunit. The EIII gene sequence typically encodes epitopes recognized by virus-specific, potently neutralizing antibodies, and EIII is believed to play a major role in receptor binding. In order to assess potential interactions between EIII and the remainder of the E protein and to assess the effects of EIII sequence substitutions on the antigenicity, growth, and virulence of a representative flavivirus, chimeric viruses were generated using the West Nile virus (WNV) infectious clone, into which EIIIs from nine flaviviruses with various levels of genetic diversity from WNV were substituted. Of the constructs tested, chimeras containing EIIIs from Koutango virus (KOUV), Japanese encephalitis virus (JEV), St. Louis encephalitis virus (SLEV), and Bagaza virus (BAGV) were successfully recovered. Characterization of the chimeras in vitro and in vivo revealed differences in growth and virulence between the viruses, within vivo pathogenesis often not being correlated within vitro growth. Taken together, the data demonstrate that substitutions of EIII can allow the generation of viable chimeric viruses with significantly altered antigenicity and virulence.
  
  
  OBJECTIVE
  The envelope (E) glycoprotein is the major protein present on the surface of flavivirus virions and is responsible for mediating virus binding and entry into target cells. Several viable West Nile virus (WNV) variants with chimeric E proteins in which the putative receptor-binding domain (EIII) sequences of other mosquito-borne flaviviruses were substituted in place of the WNV EIII were recovered, although the substitution of several more divergent EIII sequences was not tolerated. The differences in virulence and tissue tropism observed with the chimeric viruses indicate a significant role for this sequence in determining the pathogenesis of the virus within the mammalian host. Our studies demonstrate that these chimeras are viable and suggest that such recombinant viruses may be useful for investigation of domain-specific antibody responses and the more extensive definition of the contributions of EIII to the tropism and pathogenesis of WNV or other flaviviruses.
authors.affiliation: Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: McAuley
authors.affiliation: Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Maricela
authors.initials: M
authors.lastname: Torres
authors.affiliation: Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA.|Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Plante
authors.affiliation: Arbovirus Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Fort Collins, Colorado, USA.
authors.forename: Claire Y-H
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA.|Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, USA.|Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Bente
authors.affiliation: Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, USA dwbeasle@utmb.edu.|Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA.|Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, USA.|Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: David W C
authors.initials: DWC
authors.lastname: Beasley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D000956:Antigens, Viral / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D004195:Disease Models, Animal; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D005260:Female; D051379:Mice; D050296:Microbial Viability / Q000276:immunology; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D054730:Protein Interaction Domains and Motifs / Q000235:genetics / Q000276:immunology*; D016415:Sequence Alignment; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D019562:Viral Load; D010948:Viral Plaque Assay; D014774:Virulence; D014779:Virus Replication; D014901:West Nile Fever / Q000276:immunology / Q000821:virology; D014902:West Nile virus / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000956:Antigens, Viral; D000939:Epitopes; D014759:Viral Envelope Proteins