The antler velvet sample from elk 01-0306, which produced detectable amplification products after 3 rounds of PMCA, caused disease in Tg(CerPrP 1536+/– mice (mean incubation time 442 d, attack rate 75%) and in Tg(CerPrP-E226 5037+/– CerPrP-E226 5037+/
Identification of human susceptibility genes in rare diseases is challenging; therefore, parallel studies have also been carried out in mice using incubation time as a phenotype.
Indeed the mice reconstituted with BM from Prp0/0 mice have the same incubation time as mice reconstituted with BM from wild type mice, or from mice overexpressing PrPc, even when inoculated with limiting prion doses.
Consistent with this interpretation, despite 5-fold lower levels of transgene expression in Tg(CerPrP-E226 5029+/– CerPrP-E226 5029+/rPrP)1536+/– mice, mean incubathan tines of Tge D92 isolate were equivalent in these 2 lines (Table).
Whether different prognosis of HCC in mice and human reflects the species difference, or simply more infected mice and/or longer incubation time are needed to score HCC in the mice, remain to be determined.
More notably, both lines of TgPrP S3.F88W) mice had incubation times at least 60 days shorter than WT mice (Table 2): 84 and 89 day averages for TgPrP S3.F88W -35 and TgPrP S3.F88W -14 (**** P = 1.75E-18 and 2.44E-19, respectiversusersus WT control).
D-luciferin was then injected intraperitoneously (50 mg/kg body weight, Luciferin-EF™, Promega France) and after 5 min incubation time mice were placed in the dark box chamber.
As with human disease, the main genetic determinant of incubation time in mouse is variation in the prion gene, Prnp, where Prnpa (108-Leu, 189-Thr) and Prnpb (108-Phe, 189-Val) are associated short and long incubation times respectively [7] [10].
The first tested condition employed anti-5-methylcytosine Mouse mAb with a 2 hr incubation time followed by incubation with sheep anti-mouse IgG for 2 hrs, as described previously [ 25].
To test whether AD susceptibility genes are also quantitative trait genes for prion disease incubation time in mice we analysed Clu, Picalm and Cr1 in our HS mice as described above [21], [22].
