title: Transplacental transmission of Bluetongue virus serotype 1 and serotype 8 in sheep: virological and pathological findings.
abstract: The Bluetongue virus serotype 8 (BTV-8) strain, which emerged in Europe in 2006, had an unusually high ability to cause foetal infection in pregnant ruminants. Other serotypes of BTV had already been present in Europe for more than a decade, but transplacental transmission of these strains had never been demonstrated. To determine whether transplacental transmission is a unique feature of BTV-8 we compared the incidence and pathological consequences of transplacental transmission of BTV-8 to that of BTV-1. Nine pregnant ewes were infected with either BTV-8 or BTV-1. The BTV strains used for the infection were field strains isolated on embryonated chicken eggs and passaged twice on mammalian cells. Blood samples were taken to monitor the viraemia in the ewes. Four weeks after the infection, the foetuses were examined for pathological changes and for the presence of BTV. BTV-8 could be demonstrated in 12 foetuses (43%) from 5 ewes (56%). %). BTV-1 was detected in 14 foetuses (82%) from 6 ewes (67%). Pathological changes were mainly found in the central nervous system. In the BTV-8 group, lympho-histiocytic infiltrates, gliosis and slight vacuolation of the neuropil were found. BTV-1 infection induced a severe necrotizing encephalopathy and severe meningitis, with macroscopic hydranencephaly or porencephaly in 8 foetuses. In our experimental setting, using low passaged virus strains, BTV-1 was able to induce transplacental transmission to a higher incidence compared to BTV-8, causing more severe pathology.
authors.affiliation: Research and Development, MSD Animal Health, Boxmeer, The Netherlands.
authors.forename: Mirjam T W
authors.initials: MT
authors.lastname: van der Sluijs
authors.affiliation: Research and Development, MSD Animal Health, Boxmeer, The Netherlands.
authors.forename: Dianne P H
authors.initials: DP
authors.lastname: Schroer-Joosten
authors.affiliation: Research and Development, MSD Animal Health, Boxmeer, The Netherlands.
authors.forename: Aicha
authors.initials: A
authors.lastname: Fid-Fourkour
authors.affiliation: Animal Services and Pathology, MSD Animal Health, Boxmeer, The Netherlands.
authors.forename: Mieke P
authors.initials: MP
authors.lastname: Vrijenhoek
authors.affiliation: CoVeToP, Consultancy in Veterinary and Toxicological Pathology, Enghien, Belgium.
authors.forename: Isolde
authors.initials: I
authors.lastname: Debyser
authors.affiliation: Research and Development, MSD Animal Health, Boxmeer, The Netherlands.
authors.forename: Véronique
authors.initials: V
authors.lastname: Moulin
authors.affiliation: Central Veterinary Institute, Animal Sciences Group, Wageningen University and Research centre, Lelystad, The Netherlands ; Department of Infectious Diseases and Immunology, Virology Division, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Rob J M
authors.initials: RJ
authors.lastname: Moormann
authors.affiliation: Research and Development, MSD Animal Health, Boxmeer, The Netherlands.
authors.forename: Abraham J
authors.initials: AJ
authors.lastname: de Smit
mesh_terms: D000818:Animals; D001819:Bluetongue / Q000635:transmission*; D001820:Bluetongue virus / Q000145:classification*; D005260:Female; D015994:Incidence; D018445:Infectious Disease Transmission, Vertical; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology* / Q000821:virology; D012703:Serotyping; D012756:Sheep; D034561:Sheep, Domestic