PET-blot analysis contributes to BSE strain recognition in C57BI/6 mice

Identification of the strain of agent responsible for bovine spongiform encephalopathy (BSE) can be made histologically through the analysis of both distribution and intensity of brain vacuolar lesions after BSE transmission to mouse. Another useful way to distinguish the BSE agent from other prion strains is the study of the distribution of the abnormal prion protein (PrP ^res). For that purpose, paraffin-embedded tissue blot (PET-blot) method was applied on brains from C57BI/6 mice infected with cattle BSE, experimental sheep BSE, or feline spongiform encephalopathy (FSE) from a cheetah. PrP^res distribution was comparable, whichever of the three BSE agent sources was considered and was distinct from the PrP^res distribution in C57BI/6 mice inoculated with a French scrapie isolate or with a mouse-adapted scrapie strain (C506M3). These data confirm a common origin of infectious agent responsible for the British and French cattle BSE. They also indicate that PET-blot method appears as a precise complementary tool in prion strain studies because it offers easy and quick assessment of the PrP ^res mapping. Advantages and limits of the PET-blot method are discussed and compared with other established and validated methods of strain typing.