title: Reassortment between two serologically unrelated bluetongue virus strains is flexible and can involve any genome segment.
abstract: Coinfection of a cell by two different strains of a segmented virus can give rise to a "reassortant" with phenotypic characteristics that might differ from those of the parental strains. Bluetongue virus (BTV) is a double-stranded RNA (dsRNA) segmented virus and the cause of bluetongue, a major infectious disease of livestock. BTV exists as at least 26 different serotypes (BTV-1 to BTV-26). Prompted by the isolation of a field reassortant between BTV-1 and BTV-8, we systematically characterized the process of BTV reassortment. Using a reverse genetics approach, our study clearly indicates that any BTV-1 or BTV-8 genome segment can be rescued in the heterologous "backbone." To assess phenotypic variation as a result of reassortment, we examined viral growth kinetics and plaque sizes in in vitro experiments and virulence in an experimental mouse model of bluetongue disease. The monoreassortants generated had phenotypes that were very similar to those of the parental wild-type strains both in vitro and in vivo. Using a forward genetics approach in cells coinfected with BTV-1 and BTV-8, we have shown that reassortants between BTV-1 and BTV-8 are generated very readily. After only four passages in cell culture, we could not detect wild-type BTV-1 or BTV-8 in any of 140 isolated viral plaques. In addition, most of the isolated reassortants contained heterologous VP2 and VP5 structural proteins, while only 17% had homologous VP2 and VP5 proteins. Our study has shown that reassortment in BTV is very flexible, and there is no fundamental barrier to the reassortment of any genome segment. Given the propensity of BTV to reassort, it is increasingly important to have an alternative classification system for orbiviruses.
authors.affiliation: MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Shaw
authors.forename: Maxime
authors.initials: M
authors.lastname: Ratinier
authors.forename: Sandro Filipe
authors.initials: SF
authors.lastname: Nunes
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Nomikou
authors.forename: Marco
authors.initials: M
authors.lastname: Caporale
authors.forename: Matthew
authors.initials: M
authors.lastname: Golder
authors.forename: Kathryn
authors.initials: K
authors.lastname: Allan
authors.forename: Claude
authors.initials: C
authors.lastname: Hamers
authors.forename: Pascal
authors.initials: P
authors.lastname: Hudelet
authors.forename: Stéphan
authors.initials: S
authors.lastname: Zientara
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Breard
authors.forename: Peter
authors.initials: P
authors.lastname: Mertens
authors.forename: Massimo
authors.initials: M
authors.lastname: Palmarini
mesh_terms: D000818:Animals; D001820:Bluetongue virus / Q000235:genetics* / Q000254:growth & development; D016679:Genome, Viral; D005838:Genotype; D051379:Mice; D008969:Molecular Sequence Data; D010641:Phenotype; D012367:RNA, Viral / Q000235:genetics*; D016865:Reassortant Viruses / Q000235:genetics*; D011995:Recombination, Genetic; D059386:Reverse Genetics; D017422:Sequence Analysis, DNA; D010948:Viral Plaque Assay; D015678:Viral Structural Proteins / Q000235:genetics
chemical_list: D012367:RNA, Viral; D015678:Viral Structural Proteins