title: MicroRNA reduction of neuronal West Nile virus replication attenuates and affords a protective immune response in mice.
abstract: West Nile virus (WNV) is an important agent of human encephalitis that has quickly become endemic across much of the United States since its identification in North America in 1999. While the majority (∼75%) of infections are subclinical, neurologic disease can occur in a subset of cases, with outcomes including permanent neurologic damage and death. Currently, there are no WNV vaccines approved for use in humans. This study introduces a novel vaccine platform for WNV to reduce viral replication in the central nervous system while maintaining peripheral replication to elicit strong neutralizing antibody titers. Vaccine candidates were engineered to incorporate microRNA (miRNA) target sequences for a cognate miRNA expressed only in neurons, allowing the host miRNAs to target viral transcription through endogenous RNA silencing. To maintain stability, these targets were incorporated in multiple locations within the 3'-untranslated region, flanking sequences essential for viral replication without affecting the viral open reading frame. All candidates replicated comparably to wild type WNV in vitro within cells that did not express the cognate miRNA. Insertional control viruses were also capable of neuroinvasion and neurovirulence in vivo in CD-1 mice. Vaccine viruses were safe at all doses tested and did not demonstrate mutations associated with a reversion to virulence when serially passaged in mice. All vaccine constructs were protective from lethal challenge in mice, producing 93-100% protection at the highest dose tested. Overall, this is a safe and effective attenuation strategy with broad potential application for vaccine development.
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA.
authors.forename: Terza
authors.initials: T
authors.lastname: Brostoff
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Pesavento
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Barker
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA.
authors.forename: Joan L
authors.initials: JL
authors.lastname: Kenney
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Dietrich
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA.
authors.forename: Nisha K
authors.initials: NK
authors.lastname: Duggal
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Bosco-Lauth
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA. Electronic address: abrault@cdc.gov.
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Brault
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D001921:Brain / Q000821:virology; D004261:DNA Replication; D004195:Disease Models, Animal; D051379:Mice; D035683:MicroRNAs; D016254:Mutagenesis, Insertional; D009474:Neurons / Q000502:physiology / Q000821:virology; D016366:Open Reading Frames; D034622:RNA Interference; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D014779:Virus Replication; D014901:West Nile Fever / Q000517:prevention & control; D053060:West Nile Virus Vaccines / Q000008:administration & dosage / Q000235:genetics* / Q000276:immunology*; D014902:West Nile virus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*
chemical_list: D020413:3' Untranslated Regions; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D035683:MicroRNAs; D014613:Vaccines, Attenuated; D053060:West Nile Virus Vaccines
keywords: Attenuation; Immunogenicity; Neuroinvasive; Neurovirulence; WNV; miRNA