TABLE 2.

Bioassays of individual half spleens collected from C57BL mice 70 days after intraperitoneal injection with ME7 scrapie

Age at inoculation (days)	Spleen no.	Proportion of assay mice with scrapie pathologya	Incubation period (mean ± SEM) (days)	No. of pathology negative assay mice after 400 days	Estimated titer (log10 i.c. ID50 units/g)b
0-1	1	0		9
	2	0		11
	3	0		8
	4	10/10	242 ± 5	0	4.5
	5	0		12
	6	10/10	242 ± 8	0	4.5
10	7	11/11	221 ± 6	0	5.6
	8	12/12	206 ± 8	0	6.4
	9	11/11	195 ± 3	0	7.0
	10	12/12	197 ± 2	0	6.9
14	11	11/11	209 ± 6	0	6.2
	12	10/10	224 ± 6	0	5.4
	13	12/12	207 ± 6	0	6.3
	14	12/12	198 ± 4	0	6.8
29	15	10/10	215 ± 8	0	5.9
	16	12/12	199 ± 3	0	6.8
	17	10/10	199 ± 4	0	6.8
	18	11/11	190 ± 4	0	7.2

^aMice dying of intercurrent disease before 160 days postinjection and mice for which no pathology report was possible are excluded from the data.

^bLimit of the assay was approximately 3.0 log₁₀ i.c. ID₅₀ units/g.