title: Structural insight into African horsesickness virus infection.
abstract: African horsesickness (AHS) is a devastating disease of horses. The disease is caused by the double-stranded RNA-containing African horsesickness virus (AHSV). Using electron cryomicroscopy and three-dimensional image reconstruction, we determined the architecture of an AHSV serotype 4 (AHSV-4) reference strain. The structure revealed triple-layered AHS virions enclosing the segmented genome and transcriptase complex. The innermost protein layer contains 120 copies of VP3, with the viral polymerase, capping enzyme, and helicase attached to the inner surface of the VP3 layer on the 5-fold axis, surrounded by double-stranded RNA. VP7 trimers form a second, T=13 layer on top of VP3. Comparative analyses of the structures of bluetongue virus and AHSV-4 confirmed that VP5 trimers form globular domains and VP2 trimers form triskelions, on the virion surface. We also identified an AHSV-7 strain with a truncated VP2 protein (AHSV-7 tVP2) which outgrows AHSV-4 in culture. Comparison of AHSV-7 tVP2 to bluetongue virus and AHSV-4 allowed mapping of two domains in AHSV-4 VP2, and one in bluetongue virus VP2, that are important in infection. We also revealed a protein plugging the 5-fold vertices in AHSV-4. These results shed light on virus-host interactions in an economically important orbivirus to help the informed design of new vaccines.
authors.affiliation: Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors.forename: Violeta
authors.initials: V
authors.lastname: Manole
authors.forename: Pasi
authors.initials: P
authors.lastname: Laurinmäki
authors.forename: Wouter
authors.initials: W
authors.lastname: Van Wyngaardt
authors.forename: Christiaan A
authors.initials: CA
authors.lastname: Potgieter
authors.forename: Isabella M
authors.initials: IM
authors.lastname: Wright
authors.forename: Gert J
authors.initials: GJ
authors.lastname: Venter
authors.forename: Alberdina A
authors.initials: AA
authors.lastname: van Dijk
authors.forename: B Trevor
authors.initials: BT
authors.lastname: Sewell
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Butcher
mesh_terms: D000355:African Horse Sickness / Q000378:metabolism; D000356:African Horse Sickness Virus / Q000378:metabolism / Q000648:ultrastructure*; D000818:Animals; D036022:Capsid Proteins / Q000737:chemistry / Q000378:metabolism; D002522:Chlorocebus aethiops; D006736:Horses / Q000821:virology; D008958:Models, Molecular; D012330:RNA, Double-Stranded / Q000737:chemistry / Q000378:metabolism; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D014709:Vero Cells; D014758:Viral Core Proteins / Q000737:chemistry / Q000378:metabolism; D014771:Virion / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D036022:Capsid Proteins; D012330:RNA, Double-Stranded; D012367:RNA, Viral; C113737:VP3 protein, African horse sickness virus; C442560:VP5 protein, African horse sickness virus; D014758:Viral Core Proteins; D012324:RNA-Dependent RNA Polymerase