Biochemical typing of scrapie strains

Abstract

Biochemical typing of scrapie strainsDifferences in the molecular heterogeneity of the abnormal isoforms of the prion protein, PrP 5 c, due to differential glycosylation and partial endogenous or exogenous proteo-lysis1'2 have been found in different scrapie strains\ sources of Creutzfeldt-Jakob disease (CJD) and fatal familial insomnia (FFI) 4 ';, Recently Collinge et a/. 6 extended this analysis to include sporadic CJD and the new variant of Creutzfeldt-Jakob disease ( vCJD) and found that the vCJD 'type 4' pattern of PrPSc was common to mice, cats and monkeys infected with bovine spongiform encephalopathy (BSE). We have extended this analysis to include scrapie strains passaged in mice and originally derived from sheep or goats.Collinge et a/. 6 suggested that the prion molecular phenotype 'type 4' was distinct and characteristic ofBSE, and that its presence in vCJD was further evidence of a direct link between vCJD and BSE. Furthermore, they suggested that this pattern, though also seen in FPC, might be used to identify a BSE origin of the disease-in particular that it would differentiate BSE and natural scrapie in sheep and goats. Unfortunately, no control data of scrapie in mice or the other species were given to support this idea.We present a glycoform ratio analysis of mouse-passaged scrapie strains from sheep or goats and compare them with a BSE-60 ~ I 20 40 60 80 100 PrPSetn high Mr glyco!Ofm (%)

Molecular Analysis of the Protease-Resistant Prion Protein in Scrapie and Bovine Spongiform Encephalopathy Transmitted to Ovine Transgenic and Wild-Type Mice

“…It is particularly noteworthy that, for each of the different strains, glycoform ratios observed in ovine transgenic mice were consistent with those previously described for wild-type mice (4,35,50). A possible relation of strain-specific glycoform distribution with the neuroanatomical targeting of infection has been considered (21,49), but conflicting results were discussed regarding some possible differences of PrP res glycoform ratios between different neuroanatomical regions in a single TSE-infected host (35,49).…”

“…Our data indeed show that the major differences observed in wild-type mice regarding electrophoretic features of these strains (4,27,35,50) were maintained in ovine transgenic mice, including differences in both glycoform ratios and molecular sizes. In both lines of mice, BSE and 87V shared high levels of diglycosylated PrP res and low molecular masses of the unglycosylated PrP res (35,50). In contrast, Chandler and 79A strains also maintained in ovine transgenic mice their characteristic low levels of diglycosylated PrP res , as reported for wild-type mice (4,35).…”

“…In most cases, it has been difficult to identify different electrophoretic patterns in sheep with natural scrapie (6,27,30,31,52,53), in contrast with the known diversity of PrP res molecular features found among scrapie strains in wild-type mice (34,35,50). In sheep, PrP res glycoform ratios did not clearly differ from that found in cattle-BSE and did not reveal distinct subgroups of natural scrapie (6,27,52,53).…”

“…However, different features of the PrP res protein have been found in mice infected with different biological strains of scrapie, including different electrophoretic patterns demonstrated by Western blotting (4,32,34,35,50). This had also been described for strains isolated in hamster from transmissible mink encephalopathy (7)(8)(9)(10).…”

Atypical/Nor98 scrapie: properties of the agent, genetics, and epidemiology

“…In some cases, such differences are remarkably robust and are widely used as indicators for prion strain typing [11,20,38]. Nevertheless, due to the lack of use of common standardised diagnostic tools between different TSE laboratories, it is today difficult to give a consistent description of the relative ratios of the multiple bands of PrP Sc from the atypical/Nor98 scrapie isolates.…”