Infection route-independent accumulation of splenic abnormal prion protein

Abstract

The accumulation kinetics of the abnormal form of prion protein (PrPSc) in spleens and brains of scrapie (Obihiro-1)-infected mice at various times after intracerebral (i.c.), intraperitoneal (i.p.), or oral inoculation were studied. PrPSc was first detected by Western blotting with anti-prion protein antibodies on days 70 and 116 after i.c. (3 μg) in spleens and brains, respectively. Although the amount of cerebral PrPSc gradually increased to the maximum level on day 152 after i.c. inoculation, splenic PrPSc established the maximum level on day 116 after i.c. inoculation then registered slight decreases up to day 152 with farther incubation. The detectable levels of cerebral PrPSc by Western blotting were established on day 231 or 259, whereas those of splenic PrPSc were detected on day 94 or 93, after i.p. and oral infection, respectively. The splenic PrPSc decreased slightly thereafter. These results indicate that splenic PrPSc increased before cerebral PrPSc established a detectable level in a manner independent of the inoculation route.