title: A newly isolated reovirus has the simplest genomic and structural organization of any reovirus.
abstract: A total of 2,691 mosquitoes representing 17 species was collected from eight locations in southwest Cameroon and screened for pathogenic viruses. Ten isolates of a novel reovirus (genus Dinovernavirus) were detected by culturing mosquito pools on Aedes albopictus (C6/36) cell cultures. A virus that caused overt cytopathic effects was isolated, but it did not infect vertebrate cells or produce detectable disease in infant mice after intracerebral inoculation. The virus, tentatively designated Fako virus (FAKV), represents the first 9-segment, double-stranded RNA (dsRNA) virus to be isolated in nature. FAKV appears to have a broad mosquito host range, and its detection in male specimens suggests mosquito-to-mosquito transmission in nature. The structure of the T=1 FAKV virion, determined to subnanometer resolution by cryoelectron microscopy (cryo-EM), showed only four proteins per icosahedral asymmetric unit: a dimer of the major capsid protein, one turret protein, and one clamp protein. While all other turreted reoviruses of known structures have at least two copies of the clamp protein per asymmetric unit, FAKV's clamp protein bound at only one conformer of the major capsid protein. The FAKV capsid architecture and genome organization represent the most simplified reovirus described to date, and phylogenetic analysis suggests that it arose from a more complex ancestor by serial loss-of-function events.
  
  
  OBJECTIVE
  We describe the detection, genetic, phenotypic, and structural characteristics of a novel Dinovernavirus species isolated from mosquitoes collected in Cameroon. The virus, tentatively designated Fako virus (FAKV), is related to both single-shelled and partially double-shelled viruses. The only other described virus in this genus was isolated from cultured mosquito cells. It was previously unclear whether the phenotypic characteristics of that virus were reflective of this genus in nature or were altered during serial passaging in the chronically infected cell line. FAKV is a naturally occurring single-shelled reovirus with a unique virion architecture that lacks several key structural elements thought to stabilize a single-shelled reovirus virion, suggesting what may be the minimal number of proteins needed to form a viable reovirus particle. FAKV evolved from more complex ancestors by losing a genome segment and several virion proteins.
authors.affiliation: Institute for Human Infections and Immunity, Center for Tropical Diseases, and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Auguste
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, and Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Jason T
authors.initials: JT
authors.lastname: Kaelber
authors.affiliation: Department of Zoology and Animal Physiology, University of Buea, Buea, Cameroon.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Fokam
authors.affiliation: Institute for Human Infections and Immunity, Center for Tropical Diseases, and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Hilda
authors.initials: H
authors.lastname: Guzman
authors.affiliation: Department of Preclinical Sciences, Faculty of Medical Sciences, University of the West Indies, St. Augustine, Trinidad and Tobago.
authors.forename: Christine V F
authors.initials: CV
authors.lastname: Carrington
authors.affiliation: Institute for Human Infections and Immunity, Center for Tropical Diseases, and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Jesse H
authors.initials: JH
authors.lastname: Erasmus
authors.affiliation: Institut Pasteur in Bangui, Department of Virology, Bangui, Central African Republic.
authors.forename: Basile
authors.initials: B
authors.lastname: Kamgang
authors.affiliation: Institute for Human Infections and Immunity, Center for Tropical Diseases, and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Vsevolod L
authors.initials: VL
authors.lastname: Popov
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, and Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Joanita
authors.initials: J
authors.lastname: Jakana
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, and Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Xiangan
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Wood
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Widen
authors.affiliation: Institute for Human Infections and Immunity, Center for Tropical Diseases, and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Nikos
authors.initials: N
authors.lastname: Vasilakis
authors.affiliation: Institute for Human Infections and Immunity, Center for Tropical Diseases, and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Tesh
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, and Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Wah
authors.initials: W
authors.lastname: Chiu
authors.affiliation: Institute for Human Infections and Immunity, Center for Tropical Diseases, and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, USA sweaver@utmb.edu.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Weaver
mesh_terms: D000818:Animals; D002163:Cameroon; D002460:Cell Line; D016000:Cluster Analysis; D020285:Cryoelectron Microscopy; D009033:Culicidae / Q000821:virology*; D003588:Cytopathogenic Effect, Viral; D019143:Evolution, Molecular; D016679:Genome, Viral; D058507:Host Specificity; D046911:Macromolecular Substances / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D012087:Reoviridae / Q000235:genetics* / Q000302:isolation & purification* / Q000502:physiology / Q000648:ultrastructure; D017422:Sequence Analysis, DNA; D015678:Viral Structural Proteins / Q000648:ultrastructure; D014771:Virion / Q000648:ultrastructure; D014776:Virus Cultivation
chemical_list: D046911:Macromolecular Substances; D012367:RNA, Viral; D015678:Viral Structural Proteins