Strain specific and common pathogenic events in murine models of scrapie and bovine spongiform encephalopathy

To clarify the mechanisms leading to the development of Creutzfeldt-Jakob disease in some recipients of pituitary-derived human growth hormone (hGH), we investigated the effects of repeated injections of low prion doses in mice. The injections were performed, as in hGH-treated children, by a peripheral route at short intervals and for an extended period. Twelve groups of 24 mice were intraperitoneally inoculated one, two, or five times per week for 200 days with 2 ؋ 10 ؊5 to 2 ؋ 10 ؊8 dilutions of brain homogenate containing the mouse-adapted C506M3 scrapie strain. Sixteen control mice were injected once a week for 200 days with a 2 ؋ 10 ؊4 dilution of normal brain homogenate. Of mice injected in a single challenge with a scrapie inoculum of a 2 ؋ 10 ؊4 , 2 ؋ 10 ؊5 , or 2 ؋ 10 ؊6 dilution, 2/10, 1/10, and 0/10 animals developed scrapie, respectively. Control mice remained healthy. One hundred thirty-five of 135 mice injected with repeated prion doses of a 2 ؋ 10 ؊5 or 2 ؋ 10 ؊6 dilution succumbed to scrapie. Of mice injected with repeated scrapie doses of a 2 ؋ 10 ؊7 or 2 ؋ 10 ؊8 dilution, 52/59 and 38/67 animals died of scrapie, respectively. A high incidence of scrapie was observed in mice receiving repeated doses at low infectivity, whereas there was no disease in mice that were injected once with the same doses. Repeated injections of low prion doses thus constitute a risk for development of prion disease even if the same total dose inoculated in a single challenge does not induce the disease.

Section: Resultssupporting

confidence: 82%

Section: Methodsmentioning

confidence: 99%

High Incidence of Scrapie Induced by Repeated Injections of Subinfectious Prion Doses

Jacquemot

Cuche

Dormont

et al. 2005

“…The mouse scrapie strain C506M3 (7.9 ϫ 10 8 50% lethal dose/g of brain [36]) was obtained from brain homogenates of terminally ill animals. Eight-week-old C57BL/6 females (Centre d'Elevage R. Janvier, Le Genest-Saint-Isle, France) were intraperitoneally inoculated with 100 l of a 2% (wt/vol) brain homogenate.…”

Section: Methodsmentioning

confidence: 99%

Opposite Effects of Dextran Sulfate 500, the Polyene Antibiotic MS-8209, and Congo Red on Accumulation of the Protease-Resistant Isoform of PrP in the Spleens of Mice Inoculated Intraperitoneally with the Scrapie Agent

Béringue

Adjou

Lamoury

et al. 2000

The mode and the site of action of the major antiscrapie drugs have been studied by investigating their effects on the abnormal protease-resistant isoform of PrP (PrPres) and on its accumulation in mouse spleen. Dayby-day PrPres accumulation in the spleen and in other peripheral organs was first monitored to describe the early steps of scrapie pathogenesis. Three phases were identified: the detection of scrapie inoculum on the day of scrapie infection, a clearance phase, and then the peripheral accumulation of PrPres. In a second step, the effects of the polyene antibiotic MS-8209, the polyanion dextran sulfate 500 (DS500), and Congo red were assessed on these phases, after the drugs were coincubated with scrapie inoculum. Highly different mechanisms and sites of action were apparent. MS-8209 had a weak effect on the accumulation of PrPres in spleen, suggesting another site of intervention for this drug. DS500 delayed the beginning of the clearance phase but then blocked PrPres synthesis for a long period of time, probably because of its immunological effects on the spleen. Surprisingly, Congo red suppressed the clearance phase of scrapie inoculum and then increased transiently accumulation of PrPres in spleen. We showed in vitro that this effect was related to a direct enhancement of the protease resistance of PrPres by the drug.

“…It was previously shown that PrP res was more abundant in the brain of C506M3-inoculated C57BL/6 mice than in BSEinfected mice but that both strains, which otherwise had comparable incubation periods in C57BL/6 mice (about 180 days after intracerebral inoculation), were characterized by similar infectious titers at the terminal stage of the disease (26). More generally, the PrP res levels produced by a given strain appeared as a specific feature that could differentiate strains, without any apparent relationship with the duration of the incubation period (32).…”

Section: Vol 75 2001mentioning

confidence: 99%

“…The results of PrP res characterization are thus consistent with a pattern essentially determined by the more abundant PrP res species accumulating in the brain at the time of death of the animal. Following intraperitoneal inoculation of one of the strains, the level of PrP res produced by this particular strain in the brain is expected to be low at the time that mice die if they were inoculated at the same time with the other strain by the intracerebral route (26), leading to a PrP res pattern essentially determined by this intracerebrally inoculated strain. Following intracerebral inoculation of both strains, the proportion of BSE-associated PrP res may be too low to be detected.…”

Section: Vol 75 2001mentioning

confidence: 99%

Molecular Analysis of the Abnormal Prion Protein during Coinfection of Mice by Bovine Spongiform Encephalopathy and a Scrapie Agent

Baron

Biacabe

2001

Molecular features of the proteinase K-resistant prion protein (PrP res) may discriminate among prion strains, and a specific signature could be found during infection by the infectious agent causing bovine spongiform encephalopathy (BSE). To investigate the molecular basis of BSE adaptation and selection, we established a model of coinfection of mice by both BSE and a sheep scrapie strain (C506M3). We now show that the PrP res features in these mice, characterized by glycoform ratios and electrophoretic mobilities, may be undistinguishable from those found in mice infected with scrapie only, including when mice were inoculated by both strains at the same time and by the same intracerebral inoculation route. Western blot analysis using different antibodies against sequences near the putative N-terminal end of PrP res also demonstrated differences in the main proteinase K cleavage sites between mice showing either the BSE or scrapie PrP res profile. These results, which may be linked to higher levels of PrP res associated with infection by scrapie, were similar following a challenge by a higher dose of the BSE agent during coinfection by both strains intracerebrally. Whereas PrP res extraction methods used allowed us to distinguish type 1 and type 2 PrP res, differing, like BSE and scrapie, by their electrophoretic mobilities, in the same brain region of some patients with Creutzfeldt-Jakob disease, analysis of in vitro mixtures of BSE and scrapie brain homogenates did not allow us to distinguish BSE and scrapie PrP res. These results suggest that the BSE agent, the origin of which remains unknown so far but which may have arisen from a sheep scrapie agent, may be hidden by a scrapie strain during attempts to identify it by molecular studies and following transmission of the disease in mice.