title: Synthetic reconstruction of zoonotic and early human severe acute respiratory syndrome coronavirus isolates that produce fatal disease in aged mice.
abstract: The severe acute respiratory syndrome (SARS) epidemic was characterized by high mortality rates in the elderly. The molecular mechanisms that govern enhanced susceptibility of elderly populations are not known, and robust animal models are needed that recapitulate the increased pathogenic phenotype noted with increasing age. Using synthetic biology and reverse genetics, we describe the construction of a panel of isogenic SARS coronavirus (SARS-CoV) strains bearing variant spike glycoproteins that are representative of zoonotic strains found in palm civets and raccoon dogs, as well as isolates spanning the early, middle, and late phases of the SARS-CoV epidemic. The recombinant viruses replicated efficiently in cell culture and demonstrated variable sensitivities to neutralization with antibodies. The human but not the zoonotic variants replicated efficiently in human airway epithelial cultures, supporting earlier hypotheses that zoonotic isolates are less pathogenic in humans but can evolve into highly pathogenic strains. All viruses replicated efficiently, but none produced clinical disease or death in young animals. In contrast, severe clinical disease, diffuse alveolar damage, hyaline membrane formation, alveolitis, and death were noted in 12-month-old mice inoculated with the palm civet HC/SZ/61/03 strain or early-human-phase GZ02 variants but not with related middle- and late-phase epidemic or raccoon dog strains. This panel of SARS-CoV recombinants bearing zoonotic and human epidemic spike glycoproteins will provide heterologous challenge models for testing vaccine efficacy against zoonotic reintroductions as well as provide the appropriate model system for elucidating the complex virus-host interactions that contribute to more-severe and fatal SARS-CoV disease and acute respiratory distress in the elderly.
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27699-7435, USA.
authors.forename: Barry
authors.initials: B
authors.lastname: Rockx
authors.forename: Timothy
authors.initials: T
authors.lastname: Sheahan
authors.forename: Eric
authors.initials: E
authors.lastname: Donaldson
authors.forename: Jack
authors.initials: J
authors.lastname: Harkema
authors.forename: Amy
authors.initials: A
authors.lastname: Sims
authors.forename: Mark
authors.initials: M
authors.lastname: Heise
authors.forename: Raymond
authors.initials: R
authors.lastname: Pickles
authors.forename: Mark
authors.initials: M
authors.lastname: Cameron
authors.forename: David
authors.initials: D
authors.lastname: Kelvin
authors.forename: Ralph
authors.initials: R
authors.lastname: Baric
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002522:Chlorocebus aethiops; D017931:DNA Primers; D005260:Female; D008168:Lung / Q000473:pathology; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D045473:Severe acute respiratory syndrome-related coronavirus / Q000737:chemistry / Q000302:isolation & purification / Q000472:pathogenicity*; D017386:Sequence Homology, Amino Acid; D045169:Severe Acute Respiratory Syndrome / Q000473:pathology*; D064370:Spike Glycoprotein, Coronavirus; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics; D014779:Virus Replication / Q000235:genetics; D015047:Zoonoses
chemical_list: D017931:DNA Primers; D008562:Membrane Glycoproteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV