Experimental scrapie in golden Syrian hamsters: temporal comparison of in vitro cell-fusing activity with brain infectivity and histopathological changes

Abstract

Golden Syrain hamsters were inoculated intracerebrally with the hamster-adapted 263K strain of scrapie virus, and the evolution of in vitro cell fusing activity induced by brain suspensions was compared with brain infectivity titers and histological changes. Cell-fusing activity abruptly appeared 4 weeks after inoculation, 1 week before the earliest detectable histopathological changes, at an infectivity level of 7.6 log 50% lethal doses per g of brain. Cell-fusing activity was sustained throughout the remaining 4 weeks of the incubation period and the subsequent 1- to 3-week stage of clinical illness but did not increase with the logarithmic progression of infectivity, which reached a level of 11 log 50% lethal doses per g in the agonal stage of disease. Gliosis was most sensitively detected by a monoclonal antibody reacting with astrocyte intermediate filaments in an indirect immunofluorescence test, anticipating histological recognition of gliosis and spongiform change by 1 to 2 weeks. In vitro cell-fusing activity is thus one of the earliest known biological markers (apart from infectivity itself) of experimental scrapie infection.

Prions and related neurological diseases

“…However, the lack of a viremic peak before the invasion of the CNS weakens the hypothesis of the spread of scrapie agent by this route. When the infectious agent has reached the brain, it replicates at an exponential rate until the appearance of the disease (Kimberlin, 1976;Moreau Dubois et al, 1982;Kimberlin and Walker, 1986a;Pocchiari and Masullo, 1988). Each strain of scrapie and CJD produces histological lesions and PrP-res accumulation in specific brain regions and this may result, in humans, in the clinical and pathological heterogeneity described in Chapter 3.…”

Interaction of prion protein with divalent metals: possible role in neuroprotection and neurodegeneration in prion disease model

“…After harvest, MNP cells were lysed, homogenized, sonicated, and centrifuged as described previously (37,38). The supernatants were collected from cell lysates, and protein concentrations were determined and used for SDS-gel electrophoresis.…”

“…The supernatants were collected from cell lysates, and protein concentrations were determined and used for SDS-gel electrophoresis. Cytoplasmic and membrane-rich fractions containing equal amounts of protein were loaded in each lane and separated on a 15% SDS-PAGE gel as described previously (37,38).…”

“…The proteasome enzymatic assay was performed as described previously (37). In brief, after copper or control treatment, cells were collected, washed and lysed in hypotonic…”

“…Prion diseases are fatal neurodegenerative disorders that can affect both humans and animals [13,40,42,45]. Prion diseases are widely believed to be initiated by infection, ingestion, or natural formation of abnormally folded endogenous prion protein (PrP C ), resulting in a pathogenic form (PrP Sc ) [9,35,37,43]. The abnormal folding into PrP Sc results in predominant β-sheet formation in the secondary structure, unlike PrP C which consist mostly of α-helices [17,18,25,39].…”