The mice were inoculated by both intra-cerebral and intra-peritoneal routes, from a bovine thalamus sample at first passage and from pools of brains from C57Bl/6 or SJL mice at second passage.
At first passage, the mean incubation periods were not statistically different between cheetah FSE and classical cattle BSE.
On this second passage in C57Bl/6 mice using 1% brain homogenates, similar molecular features to those described at first passage (H-type) were observed in mice (26/26) surviving after 469 d.p.i.
On second passage, most of the inoculated mice showed molecular features of the abnormal prion protein (PrPd) and brain lesions similar to those observed at first passage, but clearly distinct from those of classical BSE in this mouse model.
The reason for this tendency is unclear but it had already been reported for ovine BSE transmitted to this model (296 d.p.i at first passage to 365 d.p.i at 2nd passage) [17].
After 24 h the media was changed non-adherent cells were discarded and the adherent decidualized stromal cells (DSCs) were allowed to attain confluence and used for experimentation at first passage.
When BSE agent is transmitted in this model, at first passage the mean incubation periods may vary depending on the species of the host harboring the BSE agent (cattle, sheep etc)., and was reported to be from 300 d.p.i.
However, the other mice in our experiments developed H-BSE and exhibited longer survival periods (> 491 d.p.i ., and similar biochemical and histopathological features to those observed at first passage.
PrPres was extracted and detected as previously described [15], from mice infected at first passage performed by inoculation of 10% brain homogenates with the different TSE sources from ruminants.
One subgroup showed the histopathological features seen in H-BSE at first passage, and especially a low amount of PrPd which was exclusively detected, by Congo red staining, as amyloid plaques (Figure 3A1, A2, C, E1, E2).
