1. Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
2. Immunology-Vaccinology, Fundamental and Applied Research for Animals and Health Center (FARAH), University of Liège, 4000 Liège, Belgium.
3. Electron Microscopy Unit, Veterinary and Agrochemical Research Centre (CODA-CERVA), Brussels, Belgium.