Biological activity of subfractions from scrapie-associated fibrils.
Subfractions, a nucleic acid fraction and a PrP fraction consisting of PrP17-25, a core fragment of PrPsc, were prepared from the scrapie-associated fibril-enriched fraction from scapie-affected mouse brains. The nucleic acid fraction consisted mainly of variously fragmented DNA and no scrapie-specific nucleic acid was detected in the fraction by SDS polyacrylamide gel electrophoresis. To examine the biological activity, the nucleic acid fraction was either first introduced into mouse L-929 cells before or after nuclease treatments, then transfected cell lysates prepared 2 weeks later were inoculated into mice, or directly inoculated into mice with or without the PrP fraction. The PrP fraction alone was also inoculated into mice. Mice inoculated with the transfected cell lysates or with the nucleic acid fraction alone showed no scrapie signs during their lifespan or the observation period. While 60% of the mice inoculated with the PrP fraction alone and 67% of those inoculated with the fraction together with the nucleic acid fraction showed clinical signs of scrapie. A nucleic acid molecule bound covalently to PrP17-25 was not detected. The results obtained by the present procedures so far suggest scrapie infectivity to be associated with PrPsc, which does not contain any detectable scrapie-genome molecule as either free or covalently bound nucleic acid.
Department of Veterinary Public Health, School of Veterinary Medicine, Obihiro University of Agriculture, Japan.
K
K
Sasaki
K
K
Tanaka
M
M
Ito
H
H
Isomura
M
M
Horiuchi
N
N
Ishiguro
M
M
Shinagawa
D000818:Animals; D001921:Brain / Q000382:microbiology; D001923:Brain Chemistry; D004279:DNA, Viral / Q000302:isolation & purification; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D008970:Molecular Weight; D009696:Nucleic Acids / Q000302:isolation & purification; D018620:PrPSc Proteins; D011328:Prions / Q000737:chemistry* / Q000302:isolation & purification* / Q000472:pathogenicity; D014162:Transfection
D004279:DNA, Viral; D009696:Nucleic Acids; D018620:PrPSc Proteins; D011328:Prions