NR AXKW
AU Di Bari,M.A.; Nonno,R.; Vaccari,G.; Esposito,E.; Chiappini,B.; Conte,M.; Simson,S.; Parisi,C.; D'Agostino,C.; Palazzini,N.; Agrimi,U.
TI The Bank Vole as a Bioassay for Titration Studies and Strain Characterization of Sheep Scrapie
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Epidemiology, Risk Assessment and Transmission P04.65
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB
Scrapie of sheep represents the prototype and a suitable model of prion diseases. During the course of infection, the pathological prion protein (PrPsc) progressively accumulates in nervous and several other tissues. PrPsc is a useful marker for prion diseases, but its level in a given tissue does not necessarily correlate with the infectivity titer.
Prions infectivity is quantified by end point titration or by "incubation time assay" in rodent models. However, its measurement in tissues from scrapie affected sheep is hampered by the difficult transmission of sheep scrapie to wild type rodent models.
Recently, we utilized the bank vole (Clethrionomys glareolus) for transmission studies of prion diseases from different species, including human, sheep, goat, deer, mouse and hamster.
Herein we describe the use of the bank vole as a bioassay for strain characterization and titration study on the medulla oblongata and tonsil from an ARQ/ARQ scrapie affected sheep.
Western blot analysis showed that the diglycosylated and unglycosylated bands of PrPsc appeared of higher and lower size, respectively, in tonsil than in brain. Both these sources transmitted efficiently to voles and, in spite of the aforementioned PrPsc molecular differences, the disease phenotype upon primary transmission and second passage into voles, was identical between tonsil and brain suggesting the involvement of the same strain of agent.
The infectivity titer in the brain, assessed in voles by end point titration, was 105.5 i.c. ID50/g, which was higher than that measured in wild type mice (102.9 i.c. ID50/g). By plotting Western blot signal of tonsil against brain we determined that the PrPsc concentration in tonsil was ~ 0.12% that of brain. This value correlated well with the infectivity titer estimated in tonsil by the "incubation time assay".
This study shows that: 1) the bank vole is a bioassay more sensitive than wild-type mice for infectivity studies on sheep scrapie; 2) the "incubation time assay" is a good alternative to end point titration; 3) the concentration of PrPsc in brain and tonsil correlates with their infectivity titers; 4) differences in the PrPsc molecular phenotype do not necessarily reflect the involvement of different strains.
AD Di M.A. Bari, R. Nonno, G. Vaccari, E. Esposito, B. Chiappini, M. Conte, S. Simson, C. Parisi, C. D'Agostino, N. Palazzini, U. Agrimi, Istituto Superiore di Sanità, Dep. Food Safety and Veterinary Public Health, Italy
SP englisch
PO Schottland