Table 2. PrP^Sc and infectivity in tissues from experimental (IC challenged) Atypical/Nor98 scrapie cases and natural or experimental (oral or intra-cerebral challenge) classical scrapie cases.

					PrPSC			Bioassay results
TSE isolate	Case	Case origin	Genotype	Tissue	ELISA	WB	IHC	Positive mice	Incubation period in days (mean +/−SD)	Estimated infectious titre (ID50 IC in tg338/g)
Atypical/Nor98 scrapie	8	Experimental intracerebral	AFRQ/ARQ	Cerebellum	pos	pos	pos	6/6	204+/−5	108.7
				Ileal LN	neg	neg	neg	0/6	-
				Prescapular LN	neg	neg	neg	1/5	445*	ND
				Brachial nerve	neg	neg	neg	3/5	369+/−20	ND
				External ocular muscle	neg	neg	neg	5/6	409+/−66	ND
	9	Experimental intracerebral	AHQ/AHQ	Cerebral cortex	pos	pos	pos	6/6	219+/−4	108.3
				Ileal LN	neg	neg	neg	0/6	-
				Sciatic nerve	neg	neg	neg	3/6	516+/−133	ND
				External ocular muscle	neg	neg	neg	2/6	370–450*	ND
Langlade Classical scrapie	10	Natural	VRQ/VRQ	Posterior brain stem	pos	pos	pos	6/6	221+/−20	106.8
				Spleen	pos	ND	pos	6/6	431+/−32	105.5
				Ileal LN	pos	ND	pos	6/6	436+/−66	105.5
				External ocular muscle	pos	neg	pos	6/6	427+/−29	105.6
				Semi membranous muscle	pos	neg	pos	6/6	481+/−46	105.4
	11	Experimental intracerebral	VRQ/VRQ	Posterior brain stem	pos	pos	pos	6/6	229+/−14	106.8
				Psoas muscle	pos	neg	pos	6/6	389+/−63	105.8
PG 127 Classical scrapie	12	Experimental oral	VRQ/VRQ	Posterior brain stem	pos	pos	pos	6/6	64+/−4	106.6
				Ileal LN	pos	ND	pos	6/6	78+/−3	105.5
				External ocular muscle	pos	ND	pos	6/6	81+/−2	105.1
				Psoas muscle	pos	ND	pos	6/6	87+/−7	104.5
	13	Experimental intracerebral	VRQ/VRQ	Posterior brain stem	pos	pos	pos	6/6	61+/−1	≥106.6
				Tonsil	pos	ND	pos	6/6	79+/−1	105.4
				External ocular muscle	pos	ND	pos	6/6	77+/−2	105.5

Animals were sampled at clinical stage of the disease. Mice were considered positive when abnormal PrP deposition was detected in brain. Incubation periods are presented as mean +/−SD except for that dilution with which less than 50% of mice were found positive. In that case (*) incubation periods of the positive mice are individually presented. ND: not done.

Two different methods were applied to detect PrP^Sc presence in tissue homogenate that were used for mice inoculation: WB (TeSeE WB kit – BioRad, using SHa31 as anti-PrP antibody) and ELISA (TeSeE Sheep and Goat– BioRad). Additionally when formalin fixed tissue was available PrP^Sc immunohistochemistry was also carried out (using 8G8 antibody). Infectious titres in the different tissues were estimated on the basis of incubation period in mice (Figure 4). This calculation was only performed when the attack rate was 100% and data from more than 5 animals were available.