NR AXIB
AU Andreoletti,O.; Morel,N.; Lacroux,C.; Simon,S.; Mathey,J.; Lantier,I.; Rouillon,V.; Delmas,J.M.; Weissbecker,J.L.; Corbiere,F.; Simmons,H.; Schelcher,F.; Lantier,F.; Grassi,J.
TI Dynamics and Distribution of Infectivity in Sheep Blood
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Oral Abstracts FC3.1
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Vortrag
AB In sheep disease transmission has been observed by transfusion of whole blood sampled at the end of the first half of the incubation phase. However, in this species, dynamics and distribution of the infectivity presence in blood remained poorly documented. We first characterized infectivity dynamics and distribution in blood from sheep experimentally challenged by the oral route with a 'rapid' strain. In this model clinical onset is observed as soon as 160 days post challenge. Inoculated animals were samples every month and blood was fractionated into buffy-coat, Ficoll cells and plasma. Moreover T CD4 lymphocytes, T CD8 Lymphocytes, B lymphocytes (CD45r), Mono-nucleated phagocytes (CD14) and Negative fraction (containing CD4-, CD8-, CD45r- and CD14- cells) were sorted from Ficoll preparations. Each fractions was immunoprecipitated before concentration under small volume and IC inoculation to Tg 338 (transgenic ovine PrP gene). Bioassay revealed that, infectivity (i) can be detect in this model as early as J60 post challenge (ii) is mainly linked to CD14 positive cells. Moreover this experiment provided elements indicating that infectivity presence in blood is correlated to PrPsc presence in secondary lymphoid tissue. In a second experiment, we investigated sheep naturally infected with scrapie (Langlade model). In this model, blood transfusion allowed to transmit disease as early as 3 months of age and infectivity presence in blood persisted all along the incubation phase (24 months). Moreover we demonstrated that animals contracting scrapie through transfusion were contaminant (through blood) 3 months post transfusion. In this model first results of bioassay in Tg 338 mice confirmed that most infectious blood fractions are the mononucleated cells and more particularly CD14. Finally, the efficiency of contamination by blood transfusion was established by comparison to IV inoculation using a titrated (in Tg 338 mice) inoculum. Results revealed that a 200ml whole blood transfusion was as efficient as and IV inoculation with 5105 DL50. This result contrasts with the low infectivity level observed by direct blood bioassay in Tg338 mice. This element could suggest that infectivity in whole blood is supported by a highly efficient mechanism. Both dynamics and nature of the infectivity positive fractions are of interest with regards to (i) the development and evaluation of diagnostic test on live animals and (ii) human blood sanitary policy.
AD O. Andreoletti, C. Lacroux, J. Mathey, V. Rouillon, J.M. Delmas, F. Corbière, F. Schelcher, ENVT, UMR Inra ENVT, France; N. Morel, S. Simon, J. Grassi, iBiTec-S, Service de Pharmacologie et d'Immunoanalyse, CEA/Saclay, CEA, France; I. Lantier, F. Lantier, Centre Inra de Tours, Inra Iasp, France; J.L. Weissbecker, Domaine Expérimental de Langlade, Inra Domaine Expérimental de Langlade, France; H. Simmons, ASU, Woodham Lane New Haw -Surrey KT15 3NB, VLA Weybridge, UK
SP englisch
PO Schottland