title: Development of live-attenuated arenavirus vaccines based on codon deoptimization.
abstract: Arenaviruses have a significant impact on public health and pose a credible biodefense threat, but the development of safe and effective arenavirus vaccines has remained elusive, and currently, no Food and Drug Administration (FDA)-licensed arenavirus vaccines are available. Here, we explored the use of a codon deoptimization (CD)-based approach as a novel strategy to develop live-attenuated arenavirus vaccines. We recoded the nucleoprotein (NP) of the prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) with the least frequently used codons in mammalian cells, which caused lower LCMV NP expression levels in transfected cells that correlated with decreased NP activity in cell-based functional assays. We used reverse-genetics approaches to rescue a battery of recombinant LCMVs (rLCMVs) encoding CD NPs (rLCMV/NP(CD)) that showed attenuated growth kinetics in vitro. Moreover, experiments using the well-characterized mouse model of LCMV infection revealed that rLCMV/NP(CD1) and rLCMV/NP(CD2) were highly attenuated in vivo but, upon a single immunization, conferred complete protection against a subsequent lethal challenge with wild-type (WT) recombinant LCMV (rLCMV/WT). Both rLCMV/NP(CD1) and rLCMV/NP(CD2) were genetically and phenotypically stable during serial passages in FDA vaccine-approved Vero cells. These results provide proof of concept of the safety, efficacy, and stability of a CD-based approach for developing live-attenuated vaccine candidates against human-pathogenic arenaviruses.
  
  
  OBJECTIVE
  Several arenaviruses cause severe hemorrhagic fever in humans and pose a credible bioterrorism threat. Currently, no FDA-licensed vaccines are available to combat arenavirus infections, while antiarenaviral therapy is limited to the off-label use of ribavirin, which is only partially effective and is associated with side effects. Here, we describe the generation of recombinant versions of the prototypic arenavirus LCMV encoding codon-deoptimized viral nucleoproteins (rLCMV/NP(CD)). We identified rLCMV/NP(CD1) and rLCMV/NP(CD2) to be highly attenuated in vivo but able to confer protection against a subsequent lethal challenge with wild-type LCMV. These viruses displayed an attenuated phenotype during serial amplification passages in cultured cells. Our findings support the use of this approach for the development of safe, stable, and protective live-attenuated arenavirus vaccines.
authors.affiliation: Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA.
authors.forename: Benson Yee Hin
authors.initials: BY
authors.lastname: Cheng
authors.affiliation: Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA.
authors.forename: Emilio
authors.initials: E
authors.lastname: Ortiz-Riaño
authors.affiliation: Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA.
authors.forename: Aitor
authors.initials: A
authors.lastname: Nogales
authors.affiliation: Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, USA luis_martinez@urmc.rochester.edu juanct@scripps.edu.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: de la Torre
authors.affiliation: Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA luis_martinez@urmc.rochester.edu juanct@scripps.edu.
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Sobrido
mesh_terms: D000818:Animals; D001117:Arenaviridae Infections / Q000276:immunology / Q000473:pathology / Q000517:prevention & control* / Q000821:virology; D002522:Chlorocebus aethiops; D003062:Codon; D004195:Disease Models, Animal; D015870:Gene Expression; D042822:Genomic Instability; D008217:Lymphocytic choriomeningitis virus / Q000235:genetics / Q000254:growth & development* / Q000276:immunology*; D008297:Male; D051379:Mice; D016019:Survival Analysis; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D014709:Vero Cells; D014765:Viral Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D014776:Virus Cultivation; D014779:Virus Replication
chemical_list: D003062:Codon; D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic; D014765:Viral Vaccines