Strain-specified characteristics of mouse synthetic prions

Abstract

Synthetic prions were produced in our laboratory by using recombinant mouse prion protein (MoPrP) composed of residues 89-230. The first mouse synthetic prion strain (MoSP1) was inoculated into transgenic (Tg) 9949 mice expressing N-terminally truncated MoPrP(Δ23-88) and WT FVB mice expressing full-length MoPrP. On first and second passage in Tg9949 mice, MoSP1 prions caused disease in 516 ± 27 and 258 ± 25 days, respectively; numerous, large vacuoles were found in the brainstem and gray matter of the cerebellum. MoSP1 prions passaged in Tg9949 mice were inoculated into FVB mice; on first and second passage, the FVB mice exhibited incubation times of 154 ± 4 and 130 ± 3 days, respectively. In FVB mice, vacuolation was less intense but more widely distributed, with numerous lesions in the hippocampus and cerebellar white matter. This constellation of widespread neuropatho-logic changes was similar to that found in FVB mice inoculated with Rocky Mountain Laboratory (RML) prions, a strain derived from a sheep with scrapie. Conformational stability studies showed that the half-maximal GdnHCl (Gdn 1/2 ) concentration for denaturation of MoSP1 prions passaged in Tg9949 mice was ≈4.2 M; passage in FVB mice reduced the Gdn 1/2 value to ≈1.7 M. RML prions passaged in either Tg9949 or FVB mice exhibited Gdn 1/2 values of ≈1.8 M. The incubation times, neuropathological lesion profiles, and Gdn 1/2 values indicate that MoSP1 prions differ from RML and many other prion strains derived from sheep with scrapie and cattle with bovine spongiform encephalopathy.

Formation of native prions from minimal components in vitro

“…(i) Recombinant PrP amyloid fibrils may interact with endogenous polyanions in situ after inoculation. An observation consistent with this possible explanation is that synthetic prions formed from recombinant PrP molecules display unique biochemical and neuropathological strain properties upon initial inoculation into transgenic mice expressing truncated PrP C molecules but subsequently cause typical scrapie (resembling infection with the murine RML prion strain) upon serial passage into wild-type mice (2,46). (ii) Polyanions may not be absolutely required to form an infectious prion, but may increase the efficiency of prion conversion.…”

“…Standard bioassay and neuropathology techniques were used to measure prion infectivity and strain properties (56). PrP Sc stability was assayed as described (46). Detailed descriptions for each of these techniques, statistical methods, and chemical analyses are provided in SI Materials and Methods.…”

Prion detection by an amyloid seeding assay

“…The 301V strain was derived from bovine spongiform encephalopathy prions passaged through mice (19). MoSP1 results from serial passage of synthetic prions through Tg9949 mice (15,20). Both 301V and MoSP1 efficiently seeded amyloid formation from recMoPrP(89-230) ( Fig.…”

Continuum of prion protein structures enciphers a multitude of prion isolate-specified phenotypes

“…6 and 7, which are published as supporting information on the PNAS web site). Although the [Gdn⅐HCl] 1/2 of PrP Sc for a particular prion strain (19) was similar by the two methods, the Western blot protocol did not (55). ‡ SEM for the ͓Gdn⅐HCl͔1/2 value for prion strain 139A was not determined because the conformational-stability curves could not be fitted for statistical analysis (see Fig.…”