Strain characterization of natural sheep scrapie and comparison with BSE.
Scrapie was transmitted to mice from ten sheep, collected in the UK between 1985 and 1994. As in previous natural scrapie transmissions, the results varied between scrapie sources in terms of the incidence of disease, incubation periods and neuropathology in challenged mice. This contrasted with the uniformity seen in transmissions of BSE to mice. The scrapie and BSE isolates were characterized further by serial passage in mice. Different TSE strains were isolated from each source according to the Sinc or PrP genotype of the mouse used for passage. The same two mouse-passaged strains, 301C and 301V, were isolated from each of three BSE sources. Despite the variation seen in the primary transmissions of scrapie, relatively few mouse-passaged scrapie strains were isolated and these were distinct from the BSE-derived strains. The ME7 scrapie strain, which has often been isolated from independent sheep sources in the past, was identified in isolates from four of the sheep. However, a new distinct strain, 221C, was derived from a further four scrapie sheep. These results suggest that there is agent strain variation in natural scrapie in sheep and that the spectrum of strains present may have changed over the last 20 years. The tested sample is too small to come to any conclusions about whether the BSE strain is present in sheep, but the study provides a framework for further more extensive studies.
Bruce
Moira E
ME
Institute for Animal Health, Neuropathogenesis Unit, Ogston Building,West Mains Road, Edinburgh EH9 3JF, UK1.
Boyle
Aileen
A
Institute for Animal Health, Neuropathogenesis Unit, Ogston Building,West Mains Road, Edinburgh EH9 3JF, UK1.
Cousens
Simon
S
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK2.
McConnell
Irene
I
Institute for Animal Health, Neuropathogenesis Unit, Ogston Building,West Mains Road, Edinburgh EH9 3JF, UK1.
Foster
James
J
Institute for Animal Health, Neuropathogenesis Unit, Ogston Building,West Mains Road, Edinburgh EH9 3JF, UK1.
Goldmann
Wilfred
W
Institute for Animal Health, Neuropathogenesis Unit, Ogston Building,West Mains Road, Edinburgh EH9 3JF, UK1.
Fraser
Hugh
H
Institute for Animal Health, Neuropathogenesis Unit, Ogston Building,West Mains Road, Edinburgh EH9 3JF, UK1.
D000818:Animals; D002417:Cattle; D016643:Encephalopathy, Bovine Spongiform / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology* / Q000635:transmission; D019143:Evolution, Molecular; D014644:Genetic Variation; D005838:Genotype; D015994:Incidence; D051379:Mice; D008810:Mice, Inbred C57BL; D018620:PrPSc Proteins / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D012608:Scrapie / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology* / Q000635:transmission; D012692:Serial Passage; D012756:Sheep / Q000235:genetics / Q000378:metabolism*; D015996:Survival Rate; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology
D018620:PrPSc Proteins