TABLE 3.

Frequency of SIV_mac251 detection in immunized and naive animals after i.v. challenge (groups A through E)

Animal	Virus detectiona at indicated no. of mo after challenge
	1	2	4	6	7	8	9	12	14	16
Vaccinees
269	+	+	+	−	−	+	−	−	−	−
270	+	+	−	−	−	−	+	+	−	+ (dead)
273	+	−	+	−	−	−	−	−	−	−
274	+	+	+	+	−	−	−	+	−	−
276	+	+	+	+	−	−	−	−	−	−
280	+	+	−	−	+	+	+	ND	−	+
271	+	+	+	Dead
277	+	+	+	Dead
272	+	+	+	−	+	Dead
275	+	+	+	−	+	Dead
268	+	+	+	+	+	+	+	+	+	+
278	+	+	+	+	+	+	+	+	+	+
Controls
284	+	+	+	+ (dead)
287	+	+	+	+	+	+ (dead)
282	+	+	+	+	+	+	+	ND	ND	NDb
279	+	+	+	ND	+	+	+ (dead)
283	+	+	+	+	+	+	+	ND	+	+
286	+	+	+	+	+	+	ND	Dead
285	+	+	+	−	+	+	+	ND	+	−b
281	+	+	−	−	+	−	+	ND	−	−

^a+, positive for virus isolation; −, negative for virus isolation; ND, not done; dead, the animal was dead at the time of sample. 

^bThe animal died during the preparation of this paper.