title: Viral replication kinetics and in vitro cytopathogenicity of parental and reassortant strains of bluetongue virus serotype 1, 6 and 8.
abstract: Bluetongue virus (BTV), a segmented dsRNA virus, is the causative agent of bluetongue (BT), an economically important viral haemorrhagic disease of ruminants. Bluetongue virus can exchange its genome segments in mammalian or insect cells that have been co-infected with more than one strain of the virus. This process, may potentially give rise to the generation of novel reassortant strains that may differ from parental strains in regards to their phenotypic characteristics. To investigate the potential effects of reassortment on the virus' phenotype, parental as well as reassortant strains of BTV serotype 1, 6, 8, that were derived from attenuated and wild type strains by reverse genetics, were studied in vitro for their virus replication kinetics and cytopathogenicity in mammalian (Vero) cell cultures. The results indicate that genetic reassortment can affect viral replication kinetics, the cytopathogenicity and extent/mechanism of cell death in infected cell cultures. In particular, some reassortants of non-virulent vaccine (BTV-1 and BTV-6) and virulent field origin (BTV-8) demonstrate more pronounced cytopathic effects compared to their parental strains. Some reassortant strains in addition replicated to high titres in vitro despite being composed of genome segments from slow and fast replicating parental strains. The latter result may have implications for the level of viraemia in the mammalian host and subsequent uptake and transmission of reassortant strains (and their genome segments) by Culicoides vectors. Increased rates of CPE induction could further suggest a higher virulence for reassortant strains in vivo. Overall, these findings raise questions in regards to the use of modified-live virus (MLV) vaccines and risk of reassortment in the field. To further address these questions, additional experimental infection studies using insects and/or animal models should be conducted, to determine whether these results have significant implications in vivo.
authors.affiliation: Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, Pretoria 0110, South Africa; Department of Production Animal Clinical Sciences, Norwegian University of Life Sciences, P.O. Box 8146, 0033 Oslo, Norway. Electronic address: peter.coetzee@yahoo.com.
authors.forename: Peter
authors.initials: P
authors.lastname: Coetzee
authors.affiliation: Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, Pretoria 0110, South Africa. Electronic address: moritz.vanvuuren@up.ac.za.
authors.forename: Moritz
authors.initials: M
authors.lastname: Van Vuuren
authors.affiliation: Department of Production Animal Clinical Sciences, Norwegian University of Life Sciences, P.O. Box 8146, 0033 Oslo, Norway. Electronic address: maria.stokstad@nvh.no.
authors.forename: Maria
authors.initials: M
authors.lastname: Stokstad
authors.affiliation: Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, P.O. Box 8146, 0033 Oslo, Norway. Electronic address: mette.myrmel@nvh.no.
authors.forename: Mette
authors.initials: M
authors.lastname: Myrmel
authors.affiliation: Department of Virology, Central Veterinary Institute of Wageningen University, P.O. Box 65, 8200 AB, Lelystad, The Netherlands. Electronic address: rene.vangennip@wur.nl.
authors.forename: René G P
authors.initials: RG
authors.lastname: van Gennip
authors.affiliation: Department of Virology, Central Veterinary Institute of Wageningen University, P.O. Box 65, 8200 AB, Lelystad, The Netherlands; Department of Biochemistry, Centre for Human Metabonomics, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa. Electronic address: piet.vanrijn@wur.nl.
authors.forename: Piet A
authors.initials: PA
authors.lastname: van Rijn
authors.affiliation: Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, Pretoria 0110, South Africa. Electronic address: estelle.venter@up.ac.za.
authors.forename: Estelle H
authors.initials: EH
authors.lastname: Venter
mesh_terms: D000818:Animals; D001819:Bluetongue / Q000821:virology*; D001820:Bluetongue virus / Q000235:genetics* / Q000472:pathogenicity*; D002522:Chlorocebus aethiops; D005838:Genotype; D007700:Kinetics; D010641:Phenotype; D016865:Reassortant Viruses / Q000235:genetics / Q000472:pathogenicity; D012756:Sheep; D014613:Vaccines, Attenuated; D014709:Vero Cells; D014774:Virulence / Q000235:genetics; D014779:Virus Replication / Q000235:genetics
chemical_list: D014613:Vaccines, Attenuated
keywords: Bluetongue; Bluetongue virus; Cytopathogenicity; Reassortment; Replication kinetics