Experimental bluetongue virus superinfection in calves previously immunized with bluetongue virus serotype 8
2016
Martinelle, Ludovic | Dal Pozzo, Fabiana | Sarradin, Pierre | van Campe, Willem | de Leeuw, Ilse | de Clercq, Kris | Thys, Christine | Thiry, Etienne | Saegerman, Claude | Research Unit in Epidemiology and Risk Analysis Applied to the Veterinary Sciences (UREAR-ULg), Department of Infectious and Parasitic Diseases, Center for Fundamental and Applied Research for Animal and Health (FARAH), Faculty of Veterinary Medicine ; Université de Liège = University of Liège = Universiteit van Luik = Universität Lüttich (ULiège) | Plateforme d'Infectiologie Expérimentale (PFIE) ; Institut National de la Recherche Agronomique (INRA) | Animal Experimental Centre ; Centre d'Étude et de Recherches Vétérinaires et Agrochimiques (CODA-CERVA) | Unit Vesicular and Exotic Diseases ; Centre d'Étude et de Recherches Vétérinaires et Agrochimiques (CODA-CERVA) | Veterinary Virology and Animal Viral Diseases, Department of Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, Center for Fundamental and Applied Research for Animal and Health (FARAH) ; Université de Liège = University of Liège = Universiteit van Luik = Universität Lüttich (ULiège) | Federal Public Service Health, Food Chain Safety and Environment (EPI-EMERGE, contract RF6190), Brussels, Belgium - “Fonds Spéciaux pour la Recherche-Crédits de démarrage” (contract D-08/26), University of Liège, Belgium - “Fonds Spéciaux pour la Recherche-gros équipements” (contract GE-08/02), University of Liège, Belgium - FRS-FNRS (FRFC Grant 2.4611.11)
The effect of a superinfection with bluetongue virus serotype 1 (BTV1) was evaluated on two groups of four calves. One group received a commercial inactivated BTV serotype 8 (BTV8) vaccine. This group and the non-vaccinated group of calves were challenged twice (4 months apart) with the European BTV8 strain isolated during the 2006-2007 epidemics. Calves were then infected with a BTV1 inoculum which was found to be unexpectedly contaminated by BTV serotype 15 (BTV15). BTV1 and BTV15 single infections were performed on two other groups of three BTV naïve calves. A severe clinical picture was obtained after superinfection with BTV1/BTV15 in both vaccinated and non-vaccinated animals and after challenge with BTV8 in non-vaccinated animals. BTV1 and BTV15 single infection caused only very slight clinical signs. After superinfection and at the viraemic peak, there were an average of above 1000 times more BTV15 genomic copies than BTV1 ones. BTV1 RNA could be detected only in the spleen of one calf whereas BTV15 RNA was found in 15 organs of seven different animals. BTV8 immunization whether it was acquired through vaccination and challenges or challenges alone did not change BTV1 or BTV15 RNA detection in superinfected animals. However in these animals a partial cross neutralization between BTV8 and BTV1 might be involved in the lower BTV1 replication versus BTV15. Infection with different serotypes can occur also in the field. Interference between virus strains, genetic reassortment and cross-protection were considered as mechanisms to explain the clinical outcomes and the other virological and immunological findings in the course of BTV1/BTV15 superinfection.
显示更多 [+] 显示较少 [-]