NR AXXW
AU Toppets,V.; Piret,J.; Minne,M.; Gabriel,A.; Jacqmot,O.; Grobet,L.; Antoine,N.
TI Do Tonsilar FDCs Express PrPc in Sheep?
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Pathology and Pathogenesis P03.51
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB
In 2007, two cases of natural scrapie were confirmed on sheep flocks in the south of Belgium. Always fatal, this endemic disease is associated with the accumulation of a pathogen prion protein (PrPsc) in the lymphoreticular system prior to neuroinvasion. PrPsc is generated by the transconformational change of a host cellular protein: PrPc. Studies on the kinetics of the prion reveal that the oral route is the main route of entrance of the pathogen agent.
Because infection is localized in tonsils at early time point of the disease, those organs and their draining lymph nodes appear to be of strong interest in the study of cells implicated in prion retention. Although the key role of FDCs in other prion diseases has been demonstrated, their implication in natural scrapie must be confirmed. Palatine, pharyngeal tonsils and medial retropharyngeal lymph nodes were removed from sheep 6 to 8 month old and cryosections were processed for immunofluorescence. The labelling of FDCs was performed by the use of FDC-B1. Cellular prion protein expression was revealed with PrPc specific antibodies.
Our data highlight that FDCs are localized in the light zone of the germinal centre. Analyses in confocal microscopy illustrated a positive PrPc network inside the germinal centre probably due to the presence of FDCs. Nevertheless, FDCs and B cells were associated in clusters and kept intimate contacts. The precise localization of PrPc expression in situ was difficult to certify. Thus, we analysed this expression on isolated FDCs clusters. Immunostainings on cytospins revealed, with no doubt, that FDCs expressed PrPc on their cytoplasmic extensions. B, T lymphocytes and macrophages appeared negative.
These results support the hypothesis that ovine FDCs could retain and replicate the pathogenic agent and could play a key role during the lymphoinvasion phase of the disease. However, could they play a role in the dissemination of the pathogen through the nervous system? Analyses of pattern's innervation of these lymph organs are now in progress to study potent neuroimmune connections.
AD V. Toppets, J. Piret, M. Minne, L. Grobet, N. Antoine, Faculty of Veterinary Medicine, University of Liege, Laboratory of Animal Histology and Embryology, Belgium; A. Gabriel, O. Jacqmot, Faculty of Veterinary Medicine, University of Liege, Laboratory of Animal Anatomy, Belgium
SP englisch
PO Schottland